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class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.16577">arXiv:2411.16577</a> <span> [<a href="https://arxiv.org/pdf/2411.16577">pdf</a>, <a href="https://arxiv.org/format/2411.16577">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> </div> <p class="title is-5 mathjax"> The JWST Weather Report from the Isolated Exoplanet Analog SIMP 0136+0933: Pressure-Dependent Variability Driven by Multiple Mechanisms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=McCarthy%2C+A+M">Allison M. McCarthy</a>, <a href="/search/?searchtype=author&query=Vos%2C+J+M">Johanna M. Vos</a>, <a href="/search/?searchtype=author&query=Muirhead%2C+P+S">Philip S. Muirhead</a>, <a href="/search/?searchtype=author&query=Biller%2C+B+A">Beth A. Biller</a>, <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J">Jacqueline Faherty</a>, <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Calamari%2C+E">Emily Calamari</a>, <a href="/search/?searchtype=author&query=Cowan%2C+N+B">Nicolas B. Cowan</a>, <a href="/search/?searchtype=author&query=Cruz%2C+K+L">Kelle L. Cruz</a>, <a href="/search/?searchtype=author&query=Gonzales%2C+E">Eileen Gonzales</a>, <a href="/search/?searchtype=author&query=Limbach%2C+M+A">Mary Anne Limbach</a>, <a href="/search/?searchtype=author&query=Liu%2C+P">Pengyu Liu</a>, <a href="/search/?searchtype=author&query=Nasedkin%2C+E">Evert Nasedkin</a>, <a href="/search/?searchtype=author&query=Suarez%2C+G">Genaro Suarez</a>, <a href="/search/?searchtype=author&query=Tan%2C+X">Xianyu Tan</a>, <a href="/search/?searchtype=author&query=O%27Toole%2C+C">Cian O'Toole</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Whiteford%2C+N">Niall Whiteford</a>, <a href="/search/?searchtype=author&query=Zhou%2C+Y">Yifan Zhou</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.16577v1-abstract-short" style="display: inline;"> Isolated planetary-mass objects share their mass range with planets but do not orbit a star. They lack the necessary mass to support fusion in their cores and thermally radiate their heat from formation as they cool, primarily at infrared wavelengths. Many isolated planetary-mass objects show variations in their infrared brightness consistent with non-uniform atmospheric features modulated by thei… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.16577v1-abstract-full').style.display = 'inline'; document.getElementById('2411.16577v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.16577v1-abstract-full" style="display: none;"> Isolated planetary-mass objects share their mass range with planets but do not orbit a star. They lack the necessary mass to support fusion in their cores and thermally radiate their heat from formation as they cool, primarily at infrared wavelengths. Many isolated planetary-mass objects show variations in their infrared brightness consistent with non-uniform atmospheric features modulated by their rotation. SIMP J013656.5+093347.3 is a rapidly rotating isolated planetary-mass object, and previous infrared monitoring suggests complex atmospheric features rotating in and out of view. The physical nature of these features is not well understood, with clouds, temperature variations, thermochemical instabilities, and infrared-emitting aurora all proposed as contributing mechanisms. Here we report JWST time-resolved low-resolution spectroscopy from 0.8 - 11 micron of SIMP J013656.5+093347.3 which supports the presence of three specific features in the atmosphere: clouds, hot spots, and changing carbon chemistry. We show that no single mechanism can explain the variations in the time-resolved spectra. When combined with previous studies of this object indicating patchy clouds and aurorae, these measurements reveal the rich complexity of the atmosphere of SIMP J013656.5+093347.3. Gas giant planets in the solar system, specifically Jupiter and Saturn, also have multiple cloud layers and high-altitude hot spots, suggesting these phenomena are also present in worlds both within and beyond our solar-system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.16577v1-abstract-full').style.display = 'none'; document.getElementById('2411.16577v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to ApJ Letters</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.14541">arXiv:2411.14541</a> <span> [<a href="https://arxiv.org/pdf/2411.14541">pdf</a>, <a href="https://arxiv.org/format/2411.14541">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> </div> <p class="title is-5 mathjax"> Protosolar D-to-H abundance and one part-per-billion PH$_{3}$ in the coldest brown dwarf </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Rowland%2C+M+J">Melanie J. Rowland</a>, <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Miles%2C+B+E">Brittany E. Miles</a>, <a href="/search/?searchtype=author&query=Su%C3%A1rez%2C+G">Genaro Su谩rez</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J+K">Jacqueline K. Faherty</a>, <a href="/search/?searchtype=author&query=Skemer%2C+A+J">Andrew J. Skemer</a>, <a href="/search/?searchtype=author&query=Beiler%2C+S+A">Samuel A. Beiler</a>, <a href="/search/?searchtype=author&query=Line%2C+M+R">Michael R. Line</a>, <a href="/search/?searchtype=author&query=Bjoraker%2C+G+L">Gordon L. Bjoraker</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Vos%2C+J+M">Johanna M. Vos</a>, <a href="/search/?searchtype=author&query=Merchan%2C+S+A">Sherelyn Alejandro Merchan</a>, <a href="/search/?searchtype=author&query=Marley%2C+M">Mark Marley</a>, <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a>, <a href="/search/?searchtype=author&query=Gharib-Nezhad%2C+E">Ehsan Gharib-Nezhad</a>, <a href="/search/?searchtype=author&query=Batalha%2C+N">Natasha Batalha</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Schneider%2C+A+C">Adam C. Schneider</a>, <a href="/search/?searchtype=author&query=Geballe%2C+T+R">T. R. Geballe</a>, <a href="/search/?searchtype=author&query=Carter%2C+A">Aarynn Carter</a>, <a href="/search/?searchtype=author&query=Allers%2C+K">Katelyn Allers</a>, <a href="/search/?searchtype=author&query=Mang%2C+J">James Mang</a>, <a href="/search/?searchtype=author&query=Apai%2C+D">D谩niel Apai</a> , et al. (2 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.14541v2-abstract-short" style="display: inline;"> The coldest Y spectral type brown dwarfs are similar in mass and temperature to cool and warm ($\sim$200 -- 400 K) giant exoplanets. We can therefore use their atmospheres as proxies for planetary atmospheres, testing our understanding of physics and chemistry for these complex, cool worlds. At these cold temperatures, their atmospheres are cold enough for water clouds to form, and chemical timesc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.14541v2-abstract-full').style.display = 'inline'; document.getElementById('2411.14541v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.14541v2-abstract-full" style="display: none;"> The coldest Y spectral type brown dwarfs are similar in mass and temperature to cool and warm ($\sim$200 -- 400 K) giant exoplanets. We can therefore use their atmospheres as proxies for planetary atmospheres, testing our understanding of physics and chemistry for these complex, cool worlds. At these cold temperatures, their atmospheres are cold enough for water clouds to form, and chemical timescales increase, increasing the likelihood of disequilibrium chemistry compared to warmer classes of planets. JWST observations are revolutionizing the characterization of these worlds with high signal-to-noise, moderate resolution near- and mid-infrared spectra. The spectra have been used to measure the abundances of prominent species like water, methane, and ammonia; species that trace chemical reactions like carbon monoxide; and even isotopologues of carbon monoxide and ammonia. Here, we present atmospheric retrieval results using both published fixed-slit (GTO program 1230) and new averaged time series observations (GO program 2327) of the coldest known Y dwarf, WISE 0855-0714 (using NIRSpec G395M spectra), which has an effective temperature of $\sim$ 264 K. We present a detection of deuterium in an atmosphere outside of the solar system via a relative measurement of deuterated methane (CH$_{3}$D) and standard methane. From this, we infer the D/H ratio of a substellar object outside the solar system for the first time. We also present a well-constrained part-per-billion abundance of phosphine (PH$_{3}$). We discuss our interpretation of these results and the implications for brown dwarf and giant exoplanet formation and evolution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.14541v2-abstract-full').style.display = 'none'; document.getElementById('2411.14541v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 7 figures, accepted to ApJ Letters</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.06802">arXiv:2409.06802</a> <span> [<a href="https://arxiv.org/pdf/2409.06802">pdf</a>, <a href="https://arxiv.org/format/2409.06802">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> </div> </div> <p class="title is-5 mathjax"> A photochemical PHO network for hydrogen-dominated exoplanet atmospheres </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Lee%2C+E+K+H">Elspeth K. H. Lee</a>, <a href="/search/?searchtype=author&query=Tsai%2C+S">Shang-Min Tsai</a>, <a href="/search/?searchtype=author&query=Moses%2C+J+I">Julianne I. Moses</a>, <a href="/search/?searchtype=author&query=Plane%2C+J+M+C">John M. C. Plane</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Klippenstein%2C+S+J">Stephen J. Klippenstein</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.06802v2-abstract-short" style="display: inline;"> Due to the detection of phosphine PH3 in the Solar System gas giants Jupiter and Saturn, PH3 has long been suggested to be detectable in exosolar substellar atmospheres too. However, to date, a direct detection of phosphine has proven to be elusive in exoplanet atmosphere surveys. We construct an updated phosphorus-hydrogen-oxygen (PHO) photochemical network suitable for simulation of gas giant hy… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.06802v2-abstract-full').style.display = 'inline'; document.getElementById('2409.06802v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.06802v2-abstract-full" style="display: none;"> Due to the detection of phosphine PH3 in the Solar System gas giants Jupiter and Saturn, PH3 has long been suggested to be detectable in exosolar substellar atmospheres too. However, to date, a direct detection of phosphine has proven to be elusive in exoplanet atmosphere surveys. We construct an updated phosphorus-hydrogen-oxygen (PHO) photochemical network suitable for simulation of gas giant hydrogen-dominated atmospheres. Using this network, we examine PHO photochemistry in hot Jupiter and warm Neptune exoplanet atmospheres at Solar and enriched metallicities. Our results show for HD 189733b-like hot Jupiters that HOPO, PO and P2 are typically the dominant P carriers at pressures important for transit and emission spectra, rather than PH3. For GJ1214b-like warm Neptune atmospheres our results suggest that at Solar metallicity PH3 is dominant in the absence of photochemistry, but is generally not in high abundance for all other chemical environments. At 10 and 100 times Solar, small oxygenated phosphorus molecules such as HOPO and PO dominate for both thermochemical and photochemical simulations. The network is able to reproduce well the observed PH3 abundances on Jupiter and Saturn. Despite progress in improving the accuracy of the PHO network, large portions of the reaction rate data remain with approximate, uncertain or missing values, which could change the conclusions of the current study significantly. Improving understanding of the kinetics of phosphorus-bearing chemical reactions will be a key undertaking for astronomers aiming to detect phosphine and other phosphorus species in both rocky and gaseous exoplanetary atmospheres in the near future. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.06802v2-abstract-full').style.display = 'none'; document.getElementById('2409.06802v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to ApJ (12 July 2024) - Accepted ApJ (20 Oct 2024)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.15950">arXiv:2407.15950</a> <span> [<a href="https://arxiv.org/pdf/2407.15950">pdf</a>, <a href="https://arxiv.org/format/2407.15950">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> </div> <p class="title is-5 mathjax"> A Tale of Two Molecules: The Underprediction of CO$_2$ and Overprediction of PH$_3$ in Late T and Y Dwarf Atmospheric Models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Beiler%2C+S+A">Samuel A. Beiler</a>, <a href="/search/?searchtype=author&query=Mukherjee%2C+S">Sagnick Mukherjee</a>, <a href="/search/?searchtype=author&query=Cushing%2C+M+C">Michael C. Cushing</a>, <a href="/search/?searchtype=author&query=Kirkpatrick%2C+J+D">J. Davy Kirkpatrick</a>, <a href="/search/?searchtype=author&query=Schneider%2C+A+C">Adam C. Schneider</a>, <a href="/search/?searchtype=author&query=Kothari%2C+H">Harshil Kothari</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.15950v1-abstract-short" style="display: inline;"> The sensitivity and spectral coverage of JWST is enabling us to test our assumptions of ultracool dwarf atmospheric chemistry, especially with regards to the abundances of phosphine (PH$_3$) and carbon dioxide (CO$_2$). In this paper, we use NIRSpec PRISM spectra ($\sim$0.8$-$5.5 $渭$m, $R\sim$100) of four late T and Y dwarfs to show that standard substellar atmosphere models have difficulty replic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15950v1-abstract-full').style.display = 'inline'; document.getElementById('2407.15950v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.15950v1-abstract-full" style="display: none;"> The sensitivity and spectral coverage of JWST is enabling us to test our assumptions of ultracool dwarf atmospheric chemistry, especially with regards to the abundances of phosphine (PH$_3$) and carbon dioxide (CO$_2$). In this paper, we use NIRSpec PRISM spectra ($\sim$0.8$-$5.5 $渭$m, $R\sim$100) of four late T and Y dwarfs to show that standard substellar atmosphere models have difficulty replicating the 4.1$-$4.4 $渭$m wavelength range as they predict an overabundance of phosphine and an underabundance of carbon dioxide. To help quantify this discrepancy, we generate a grid of models using PICASO based on the Elf Owl chemical and temperature profiles where we include the abundances of these two molecules as parameters. The fits to these PICASO models show a consistent preference for orders of magnitude higher CO$_2$ abundances and a reduction in PH$_3$ abundance as compared to the nominal models. This tendency means that the claimed phosphine detection in UNCOVER$-$BD$-$3 could instead be explained by a CO$_2$ abundance in excess of standard atmospheric model predictions; however the signal-to-noise of the spectrum is not high enough to discriminate between these cases. We discuss atmospheric mechanisms that could explain the observed underabundance of PH$_3$ and overabundance of CO$_2$, including a vertical eddy diffusion coefficient ($K_{\mathrm{zz}}$) that varies with altitude, incorrect chemical pathways, or elements condensing out in forms such as NH$_4$H$_2$PO$_4$. However, our favored explanation for the required CO$_2$ enhancement is that the quench approximation does not accurately predict the CO$_2$ abundance, as CO$_2$ remains in chemical equilibrium with CO after CO quenches. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15950v1-abstract-full').style.display = 'none'; document.getElementById('2407.15950v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted, 15 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.01694">arXiv:2407.01694</a> <span> [<a href="https://arxiv.org/pdf/2407.01694">pdf</a>, <a href="https://arxiv.org/format/2407.01694">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> </div> <p class="title is-5 mathjax"> Retrieving Young Cloudy L-Dwarfs: A Nearby Planetary-Mass Companion BD+60 1417B and Its Isolated Red Twin W0047 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Phillips%2C+C+L">Caprice L. Phillips</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J+K">Jacqueline K. Faherty</a>, <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Vos%2C+J+M">Johanna M. Vos</a>, <a href="/search/?searchtype=author&query=Gonzales%2C+E">Eileen Gonzales</a>, <a href="/search/?searchtype=author&query=Griffith%2C+E+J">Emily J. Griffith</a>, <a href="/search/?searchtype=author&query=Merchan%2C+S+A">Sherelyn Alejandro Merchan</a>, <a href="/search/?searchtype=author&query=Calamari%2C+E">Emily Calamari</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Whiteford%2C+N">Niall Whiteford</a>, <a href="/search/?searchtype=author&query=Gaarn%2C+J">Josefine Gaarn</a>, <a href="/search/?searchtype=author&query=Ilyin%2C+I">Ilya Ilyin</a>, <a href="/search/?searchtype=author&query=Strassmeier%2C+K">Klaus Strassmeier</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.01694v1-abstract-short" style="display: inline;"> We present an atmospheric retrieval analysis on a set of young, cloudy, red L-dwarfs -- CWISER J124332.12+600126.2 and WISEP J004701.06+680352.1 -- using the \textit{Brewster} retrieval framework. We also present the first elemental abundance measurements of the young K-dwarf (K0) host star, BD+60 1417 using high resolution~(R = 50,000) spectra taken with PEPSI/LBT. In the complex cloudy L-dwarf r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.01694v1-abstract-full').style.display = 'inline'; document.getElementById('2407.01694v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.01694v1-abstract-full" style="display: none;"> We present an atmospheric retrieval analysis on a set of young, cloudy, red L-dwarfs -- CWISER J124332.12+600126.2 and WISEP J004701.06+680352.1 -- using the \textit{Brewster} retrieval framework. We also present the first elemental abundance measurements of the young K-dwarf (K0) host star, BD+60 1417 using high resolution~(R = 50,000) spectra taken with PEPSI/LBT. In the complex cloudy L-dwarf regime the emergence of condensate cloud species complicates retrieval analysis when only near-infrared data is available. We find that for both L dwarfs in this work, despite testing three different thermal profile parameterizations we are unable to constrain reliable abundance measurements and thus the C/O ratio. While we can not conclude what the abundances are, we can conclude that the data strongly favor a cloud model over a cloudless model. We note that the difficulty in retrieval constraints persists regardless of the signal to noise of the data examined (S/N $\sim$ 10 for CWISER J124332.12+600126.2 and~40 for WISEP J004701.06+680352.1). The results presented in this work provide valuable lessons about retrieving young, low-surface gravity, cloudy L-dwarfs. This work provides continued evidence of missing information in models and the crucial need for JWST to guide and inform retrieval analysis in this regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.01694v1-abstract-full').style.display = 'none'; document.getElementById('2407.01694v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.00758">arXiv:2402.00758</a> <span> [<a href="https://arxiv.org/pdf/2402.00758">pdf</a>, <a href="https://arxiv.org/format/2402.00758">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> </div> <p class="title is-5 mathjax"> The Sonora Substellar Atmosphere Models. III. Diamondback: Atmospheric Properties, Spectra, and Evolution for Warm Cloudy Substellar Objects </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Mukherjee%2C+S">Sagnick Mukherjee</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Gharib-Nezhad%2C+E">Ehsan Gharib-Nezhad</a>, <a href="/search/?searchtype=author&query=Thorngren%2C+D">Daniel Thorngren</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a>, <a href="/search/?searchtype=author&query=7%2C+N+B">Natasha Batalha 7</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.00758v1-abstract-short" style="display: inline;"> We present a new grid of cloudy atmosphere and evolution models for substellar objects. These models include the effect of refractory cloud species, including silicate clouds, on the spectra and evolution. We include effective temperatures from 900 to 2400 K and surface gravities from log g=3.5-5.5, appropriate for a broad range of objects with masses between 1 and 84 Jupiter masses. Model pressur… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00758v1-abstract-full').style.display = 'inline'; document.getElementById('2402.00758v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.00758v1-abstract-full" style="display: none;"> We present a new grid of cloudy atmosphere and evolution models for substellar objects. These models include the effect of refractory cloud species, including silicate clouds, on the spectra and evolution. We include effective temperatures from 900 to 2400 K and surface gravities from log g=3.5-5.5, appropriate for a broad range of objects with masses between 1 and 84 Jupiter masses. Model pressure-temperature structures are calculated assuming radiative-convective and chemical equilibrium. We consider the effect of both clouds and metallicity on the atmospheric structure, resulting spectra, and thermal evolution of substellar worlds. We parameterize clouds using the Ackerman & Marley (2001) cloud model, including cloud parameter fsed values from 1-8; we include three metallicities (-0.5, 0.0, and +0.5). Refractory clouds and metallicity both alter the evolution of substellar objects, changing the inferred temperature at a given age by up to 100-200 K. We compare to the observed photometry of brown dwarfs, finding broad agreement with the measured photometry. We publish the spectra, evolution, and other data products online with open access. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00758v1-abstract-full').style.display = 'none'; document.getElementById('2402.00758v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">26 pages, 18 figures, submitted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.00756">arXiv:2402.00756</a> <span> [<a href="https://arxiv.org/pdf/2402.00756">pdf</a>, <a href="https://arxiv.org/format/2402.00756">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ad18c2">10.3847/1538-4357/ad18c2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Sonora Substellar Atmosphere Models. IV. Elf Owl: Atmospheric Mixing and Chemical Disequilibrium with Varying Metallicity and C/O Ratios </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Mukherjee%2C+S">Sagnick Mukherjee</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Batalha%2C+N+E">Natasha E. Batalha</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Karalidi%2C+T">Theodora Karalidi</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a>, <a href="/search/?searchtype=author&query=Gharib-Nezhad%2C+E">Ehsan Gharib-Nezhad</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.00756v1-abstract-short" style="display: inline;"> Disequilibrium chemistry due to vertical mixing in the atmospheres of many brown dwarfs and giant exoplanets is well-established. Atmosphere models for these objects typically parameterize mixing with the highly uncertain $K_{\rm zz}$ diffusion parameter. The role of mixing in altering the abundances of C-N-O-bearing molecules has mostly been explored for solar composition atmospheres. However, at… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00756v1-abstract-full').style.display = 'inline'; document.getElementById('2402.00756v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.00756v1-abstract-full" style="display: none;"> Disequilibrium chemistry due to vertical mixing in the atmospheres of many brown dwarfs and giant exoplanets is well-established. Atmosphere models for these objects typically parameterize mixing with the highly uncertain $K_{\rm zz}$ diffusion parameter. The role of mixing in altering the abundances of C-N-O-bearing molecules has mostly been explored for solar composition atmospheres. However, atmospheric metallicity and the C/O ratio also impact atmospheric chemistry. Therefore, we present the \texttt{Sonora Elf Owl} grid of self-consistent cloud-free 1D radiative-convective equilibrium model atmospheres for JWST observations, which includes a variation of $K_{\rm zz}$ across several orders of magnitude and also encompasses sub-solar to super-solar metallicities and C/O ratios. We find that the impact of $K_{\rm zz}$ on the $T(P)$ profile and spectra is a strong function of both $T_{\rm eff}$ and metallicity. For metal-poor objects $K_{\rm zz}$ has large impacts on the atmosphere at significantly higher $T_{\rm eff}$ compared to metal-rich atmospheres where the impact of $K_{\rm zz}$ is seen to occur at lower $T_{\rm eff}$. We identify significant spectral degeneracies between varying $K_{\rm zz}$ and metallicity in multiple wavelength windows, in particular at 3-5 $渭$m. We use the \texttt{Sonora Elf Owl} atmospheric grid to fit the observed spectra of a sample of 9 early to late T- type objects from $T_{\rm eff}=550-1150$ K. We find evidence for very inefficient vertical mixing in these objects with inferred $K_{\rm zz}$ values lying in the range between $\sim$ 10$^1$-10$^4$ cm$^2$s$^{-1}$. Using self-consistent models, we find that this slow vertical mixing is due to the observations probing mixing in the deep detached radiative zone in these atmospheres. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00756v1-abstract-full').style.display = 'none'; document.getElementById('2402.00756v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for Publication in The Astrophysical Journal, 16 Figures, 3 Tables, 28 Pages</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal, Volume 963, Issue 1, id.73, 26 pp, March 2024 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.11038">arXiv:2401.11038</a> <span> [<a href="https://arxiv.org/pdf/2401.11038">pdf</a>, <a href="https://arxiv.org/format/2401.11038">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> Predicting Cloud Conditions in Substellar Mass Objects Using Ultracool Dwarf Companions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Calamari%2C+E">Emily Calamari</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J+K">Jacqueline K. Faherty</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Gemma%2C+M+E">Marina E. Gemma</a>, <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Rothermich%2C+A">Austin Rothermich</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.11038v1-abstract-short" style="display: inline;"> We present results from conducting a theoretical chemical analysis of a sample of benchmark companion brown dwarfs whose primary star is of type F, G or K. We summarize the entire known sample of these types of companion systems, termed "compositional benchmarks", that are present in the literature or recently published as key systems of study in order to best understand brown dwarf chemistry and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.11038v1-abstract-full').style.display = 'inline'; document.getElementById('2401.11038v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.11038v1-abstract-full" style="display: none;"> We present results from conducting a theoretical chemical analysis of a sample of benchmark companion brown dwarfs whose primary star is of type F, G or K. We summarize the entire known sample of these types of companion systems, termed "compositional benchmarks", that are present in the literature or recently published as key systems of study in order to best understand brown dwarf chemistry and condensate formation. Via mass balance and stoichiometric calculations, we predict a median brown dwarf atmospheric oxygen sink of $17.8^{+1.7}_{-2.3}\%$ by utilizing published stellar abundances in the local solar neighborhood. Additionally, we predict a silicate condensation sequence such that atmospheres with bulk Mg/Si $\lesssim$ 0.9 will form enstatite (MgSiO$_3$) and quartz (SiO$_2$) clouds and atmospheres with bulk Mg/Si $\gtrsim$ 0.9 will form enstatite and forsterite (Mg$_2$SiO$_4$) clouds. Implications of these results on C/O ratio trends in substellar mass objects and utility of these predictions in future modeling work are discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.11038v1-abstract-full').style.display = 'none'; document.getElementById('2401.11038v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 2 tables, 4 figures. Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.08637">arXiv:2310.08637</a> <span> [<a href="https://arxiv.org/pdf/2310.08637">pdf</a>, <a href="https://arxiv.org/format/2310.08637">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> </div> <p class="title is-5 mathjax"> JWST-TST DREAMS: Quartz Clouds in the Atmosphere of WASP-17b </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Grant%2C+D">David Grant</a>, <a href="/search/?searchtype=author&query=Lewis%2C+N+K">Nikole K. Lewis</a>, <a href="/search/?searchtype=author&query=Wakeford%2C+H+R">Hannah R. Wakeford</a>, <a href="/search/?searchtype=author&query=Batalha%2C+N+E">Natasha E. Batalha</a>, <a href="/search/?searchtype=author&query=Glidden%2C+A">Ana Glidden</a>, <a href="/search/?searchtype=author&query=Goyal%2C+J">Jayesh Goyal</a>, <a href="/search/?searchtype=author&query=Mullens%2C+E">Elijah Mullens</a>, <a href="/search/?searchtype=author&query=MacDonald%2C+R+J">Ryan J. MacDonald</a>, <a href="/search/?searchtype=author&query=May%2C+E+M">Erin M. May</a>, <a href="/search/?searchtype=author&query=Seager%2C+S">Sara Seager</a>, <a href="/search/?searchtype=author&query=Stevenson%2C+K+B">Kevin B. Stevenson</a>, <a href="/search/?searchtype=author&query=Valenti%2C+J+A">Jeff A. Valenti</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Alderson%2C+L">Lili Alderson</a>, <a href="/search/?searchtype=author&query=Allen%2C+N+H">Natalie H. Allen</a>, <a href="/search/?searchtype=author&query=Ca%C3%B1as%2C+C+I">Caleb I. Ca帽as</a>, <a href="/search/?searchtype=author&query=Col%C3%B3n%2C+K">Knicole Col贸n</a>, <a href="/search/?searchtype=author&query=Clampin%2C+M">Mark Clampin</a>, <a href="/search/?searchtype=author&query=Espinoza%2C+N">N茅stor Espinoza</a>, <a href="/search/?searchtype=author&query=Gressier%2C+A">Am茅lie Gressier</a>, <a href="/search/?searchtype=author&query=Huang%2C+J">Jingcheng Huang</a>, <a href="/search/?searchtype=author&query=Lin%2C+Z">Zifan Lin</a>, <a href="/search/?searchtype=author&query=Long%2C+D">Douglas Long</a>, <a href="/search/?searchtype=author&query=Louie%2C+D+R">Dana R. Louie</a>, <a href="/search/?searchtype=author&query=Pe%C3%B1a-Guerrero%2C+M">Maria Pe帽a-Guerrero</a> , et al. (17 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.08637v2-abstract-short" style="display: inline;"> Clouds are prevalent in many of the exoplanet atmospheres that have been observed to date. For transiting exoplanets, we know if clouds are present because they mute spectral features and cause wavelength-dependent scattering. While the exact composition of these clouds is largely unknown, this information is vital to understanding the chemistry and energy budget of planetary atmospheres. In this… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.08637v2-abstract-full').style.display = 'inline'; document.getElementById('2310.08637v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.08637v2-abstract-full" style="display: none;"> Clouds are prevalent in many of the exoplanet atmospheres that have been observed to date. For transiting exoplanets, we know if clouds are present because they mute spectral features and cause wavelength-dependent scattering. While the exact composition of these clouds is largely unknown, this information is vital to understanding the chemistry and energy budget of planetary atmospheres. In this work, we observe one transit of the hot Jupiter WASP-17b with JWST's MIRI LRS and generate a transmission spectrum from 5-12 $\rm渭$m. These wavelengths allow us to probe absorption due to the vibrational modes of various predicted cloud species. Our transmission spectrum shows additional opacity centered at 8.6 $\rm渭$m, and detailed atmospheric modeling and retrievals identify this feature as SiO$_2$(s) (quartz) clouds. The SiO$_2$(s) clouds model is preferred at 3.5-4.2$蟽$ versus a cloud-free model and at 2.6$蟽$ versus a generic aerosol prescription. We find the SiO$_2$(s) clouds are comprised of small ${\sim}0.01$ $\rm渭$m particles, which extend to high altitudes in the atmosphere. The atmosphere also shows a depletion of H$_2$O, a finding consistent with the formation of high-temperature aerosols from oxygen-rich species. This work is part of a series of studies by our JWST Telescope Scientist Team (JWST-TST), in which we will use Guaranteed Time Observations to perform Deep Reconnaissance of Exoplanet Atmospheres through Multi-instrument Spectroscopy (DREAMS). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.08637v2-abstract-full').style.display = 'none'; document.getElementById('2310.08637v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 7 figures, fixed typo in Equation 3</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.16863">arXiv:2303.16863</a> <span> [<a href="https://arxiv.org/pdf/2303.16863">pdf</a>, <a href="https://arxiv.org/format/2303.16863">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stad753">10.1093/mnras/stad753 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The puzzle of the formation of T8 dwarf Ross 458c </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Gaarn%2C+J">Josefine Gaarn</a>, <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J+K">Jacqueline K. Faherty</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Gonzales%2C+E+C">Eileen C. Gonzales</a>, <a href="/search/?searchtype=author&query=Calamari%2C+E">Emily Calamari</a>, <a href="/search/?searchtype=author&query=Gagliuffi%2C+D+B">Daniella Bardalez Gagliuffi</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.16863v2-abstract-short" style="display: inline;"> At the lowest masses, the distinction between brown dwarfs and giant exoplanets is often blurred and literature classifications rarely reflect the deuterium burning boundary. Atmospheric characterisation may reveal the extent to which planetary formation pathways contribute to the population of very-low mass brown dwarfs, by revealing if their abundance distributions differ from those of the local… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.16863v2-abstract-full').style.display = 'inline'; document.getElementById('2303.16863v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.16863v2-abstract-full" style="display: none;"> At the lowest masses, the distinction between brown dwarfs and giant exoplanets is often blurred and literature classifications rarely reflect the deuterium burning boundary. Atmospheric characterisation may reveal the extent to which planetary formation pathways contribute to the population of very-low mass brown dwarfs, by revealing if their abundance distributions differ from those of the local field population or, in the case of companions, their primary stars. The T8 dwarf Ross 458c is a possible planetary mass companion to a pair of M dwarfs, and previous work suggests that it is cloudy. We here present the results of the retrieval analysis of Ross 458c, using archival spectroscopic data in the 1.0 to 2.4 micron range. We test a cloud free model as well as a variety of cloudy models and find that the atmosphere of Ross 458c is best described by a cloudy model (strongly preferred). The CH4/H2O is higher than expected at 1.97 +0.13 -0.14. This value is challenging to understand in terms of equilibrium chemistry and plausible C/O ratios. Comparisons to thermochemical grid models suggest a C/O of ~ 1.35, if CH4 and H2O are quenched at 2000 K, requiring vigorous mixing. We find a [C/H] ratio of +0.18, which matches the metallicity of the primary system, suggesting that oxygen is missing from the atmosphere. Even with extreme mixing, the implied C/O is well beyond the typical stellar regime, suggesting a either non-stellar formation pathway, or the sequestration of substantial quantities of oxygen via hitherto unmodeled chemistry or condensation processes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.16863v2-abstract-full').style.display = 'none'; document.getElementById('2303.16863v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.07399">arXiv:2212.07399</a> <span> [<a href="https://arxiv.org/pdf/2212.07399">pdf</a>, <a href="https://arxiv.org/format/2212.07399">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/acab58">10.3847/1538-4357/acab58 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Patchy Forsterite Clouds in the Atmospheres of Two Highly Variable Exoplanet Analogs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Vos%2C+J+M">Johanna M. Vos</a>, <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J+K">Jacqueline K. Faherty</a>, <a href="/search/?searchtype=author&query=Alejandro%2C+S">Sherelyn Alejandro</a>, <a href="/search/?searchtype=author&query=Gonzales%2C+E">Eileen Gonzales</a>, <a href="/search/?searchtype=author&query=Calamari%2C+E">Emily Calamari</a>, <a href="/search/?searchtype=author&query=Gagliuffi%2C+D+B">Daniella Bardalez Gagliuffi</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Tan%2C+X">Xianyu Tan</a>, <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Marley%2C+M">Mark Marley</a>, <a href="/search/?searchtype=author&query=Gemma%2C+M+E">Marina E. Gemma</a>, <a href="/search/?searchtype=author&query=Whiteford%2C+N">Niall Whiteford</a>, <a href="/search/?searchtype=author&query=Gaarn%2C+J">Josefine Gaarn</a>, <a href="/search/?searchtype=author&query=Park%2C+G">Grace Park</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.07399v1-abstract-short" style="display: inline;"> We present an atmospheric retrieval analysis of a pair of highly variable, $\sim200~$Myr old, early-T type planetary-mass exoplanet analogs SIMP J01365662+0933473 and 2MASS J21392676+0220226 using the Brewster retrieval framework. Our analysis, which makes use of archival $1-15~渭$m spectra, finds almost identical atmospheres for both objects. For both targets, we find that the data is best describ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.07399v1-abstract-full').style.display = 'inline'; document.getElementById('2212.07399v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.07399v1-abstract-full" style="display: none;"> We present an atmospheric retrieval analysis of a pair of highly variable, $\sim200~$Myr old, early-T type planetary-mass exoplanet analogs SIMP J01365662+0933473 and 2MASS J21392676+0220226 using the Brewster retrieval framework. Our analysis, which makes use of archival $1-15~渭$m spectra, finds almost identical atmospheres for both objects. For both targets, we find that the data is best described by a patchy, high-altitude forsterite (Mg$_2$SiO$_4$) cloud above a deeper, optically thick iron (Fe) cloud. Our model constrains the cloud properties well, including the cloud locations and cloud particle sizes. We find that the patchy forsterite slab cloud inferred from our retrieval may be responsible for the spectral behavior of the observed variability. Our retrieved cloud structure is consistent with the atmospheric structure previously inferred from spectroscopic variability measurements, but clarifies this picture significantly. We find consistent C/O ratios for both objects which supports their formation within the same molecular cloud in the Carina-Near Moving Group. Finally, we note some differences in the constrained abundances of H$_2$O and CO which may be caused by data quality and/or astrophysical processes such as auroral activity and their differing rotation rates. The results presented in this work provide a promising preview of the detail with which we will characterize extrasolar atmospheres with JWST, which will yield higher quality spectra across a wider wavelength range. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.07399v1-abstract-full').style.display = 'none'; document.getElementById('2212.07399v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.10490">arXiv:2211.10490</a> <span> [<a href="https://arxiv.org/pdf/2211.10490">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-023-05902-2">10.1038/s41586-023-05902-2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Photochemically-produced SO$_2$ in the atmosphere of WASP-39b </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Tsai%2C+S">Shang-Min Tsai</a>, <a href="/search/?searchtype=author&query=Lee%2C+E+K+H">Elspeth K. H. Lee</a>, <a href="/search/?searchtype=author&query=Powell%2C+D">Diana Powell</a>, <a href="/search/?searchtype=author&query=Gao%2C+P">Peter Gao</a>, <a href="/search/?searchtype=author&query=Zhang%2C+X">Xi Zhang</a>, <a href="/search/?searchtype=author&query=Moses%2C+J">Julianne Moses</a>, <a href="/search/?searchtype=author&query=H%C3%A9brard%2C+E">Eric H茅brard</a>, <a href="/search/?searchtype=author&query=Venot%2C+O">Olivia Venot</a>, <a href="/search/?searchtype=author&query=Parmentier%2C+V">Vivien Parmentier</a>, <a href="/search/?searchtype=author&query=Jordan%2C+S">Sean Jordan</a>, <a href="/search/?searchtype=author&query=Hu%2C+R">Renyu Hu</a>, <a href="/search/?searchtype=author&query=Alam%2C+M+K">Munazza K. Alam</a>, <a href="/search/?searchtype=author&query=Alderson%2C+L">Lili Alderson</a>, <a href="/search/?searchtype=author&query=Batalha%2C+N+M">Natalie M. Batalha</a>, <a href="/search/?searchtype=author&query=Bean%2C+J+L">Jacob L. Bean</a>, <a href="/search/?searchtype=author&query=Benneke%2C+B">Bj枚rn Benneke</a>, <a href="/search/?searchtype=author&query=Bierson%2C+C+J">Carver J. Bierson</a>, <a href="/search/?searchtype=author&query=Brady%2C+R+P">Ryan P. Brady</a>, <a href="/search/?searchtype=author&query=Carone%2C+L">Ludmila Carone</a>, <a href="/search/?searchtype=author&query=Carter%2C+A+L">Aarynn L. Carter</a>, <a href="/search/?searchtype=author&query=Chubb%2C+K+L">Katy L. Chubb</a>, <a href="/search/?searchtype=author&query=Inglis%2C+J">Julie Inglis</a>, <a href="/search/?searchtype=author&query=Leconte%2C+J">J茅r茅my Leconte</a>, <a href="/search/?searchtype=author&query=Lopez-Morales%2C+M">Mercedes Lopez-Morales</a>, <a href="/search/?searchtype=author&query=Miguel%2C+Y">Yamila Miguel</a> , et al. (60 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.10490v2-abstract-short" style="display: inline;"> Photochemistry is a fundamental process of planetary atmospheres that regulates the atmospheric composition and stability. However, no unambiguous photochemical products have been detected in exoplanet atmospheres to date. Recent observations from the JWST Transiting Exoplanet Early Release Science Program found a spectral absorption feature at 4.05 $渭$m arising from SO$_2$ in the atmosphere of WA… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.10490v2-abstract-full').style.display = 'inline'; document.getElementById('2211.10490v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.10490v2-abstract-full" style="display: none;"> Photochemistry is a fundamental process of planetary atmospheres that regulates the atmospheric composition and stability. However, no unambiguous photochemical products have been detected in exoplanet atmospheres to date. Recent observations from the JWST Transiting Exoplanet Early Release Science Program found a spectral absorption feature at 4.05 $渭$m arising from SO$_2$ in the atmosphere of WASP-39b. WASP-39b is a 1.27-Jupiter-radii, Saturn-mass (0.28 M$_J$) gas giant exoplanet orbiting a Sun-like star with an equilibrium temperature of $\sim$1100 K. The most plausible way of generating SO$_2$ in such an atmosphere is through photochemical processes. Here we show that the SO$_2$ distribution computed by a suite of photochemical models robustly explains the 4.05 $渭$m spectral feature identified by JWST transmission observations with NIRSpec PRISM (2.7$蟽$) and G395H (4.5$蟽$). SO$_2$ is produced by successive oxidation of sulphur radicals freed when hydrogen sulphide (H$_2$S) is destroyed. The sensitivity of the SO$_2$ feature to the enrichment of the atmosphere by heavy elements (metallicity) suggests that it can be used as a tracer of atmospheric properties, with WASP-39b exhibiting an inferred metallicity of $\sim$10$\times$ solar. We further point out that SO$_2$ also shows observable features at ultraviolet and thermal infrared wavelengths not available from the existing observations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.10490v2-abstract-full').style.display = 'none'; document.getElementById('2211.10490v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">39 pages, 14 figures, accepted to be published in Nature</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.02754">arXiv:2209.02754</a> <span> [<a href="https://arxiv.org/pdf/2209.02754">pdf</a>, <a href="https://arxiv.org/format/2209.02754">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac8f2a">10.3847/1538-4357/ac8f2a <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Comparative L-dwarf Sample Exploring the Interplay Between Atmospheric Assumptions and Data Properties </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Gonzales%2C+E+C">Eileen C. Gonzales</a>, <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J+K">Jacqueline K. Faherty</a>, <a href="/search/?searchtype=author&query=Lewis%2C+N+K">Nikole K. Lewis</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Marley%2C+M">Mark Marley</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.02754v1-abstract-short" style="display: inline;"> Comparisons of atmospheric retrievals can reveal powerful insights on the strengths and limitations of our data and modeling tools. In this paper, we examine a sample of 5 similar effective temperature (Teff) or spectral type L dwarfs to compare their pressure-temperature (P-T) profiles. Additionally, we explore the impact of an object's metallicity and the observations' signal-to-noise (SNR) on t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.02754v1-abstract-full').style.display = 'inline'; document.getElementById('2209.02754v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.02754v1-abstract-full" style="display: none;"> Comparisons of atmospheric retrievals can reveal powerful insights on the strengths and limitations of our data and modeling tools. In this paper, we examine a sample of 5 similar effective temperature (Teff) or spectral type L dwarfs to compare their pressure-temperature (P-T) profiles. Additionally, we explore the impact of an object's metallicity and the observations' signal-to-noise (SNR) on the parameters we can retrieve. We present the first atmospheric retrievals: 2MASS J15261405$+$2043414, 2MASS J05395200$-$0059019, 2MASS J15394189$-$0520428, and GD 165B increasing the small but growing number of L-dwarfs retrieved. When compared to atmospheric retrievals of SDSS J141624.08+134826.7, a low-metallicity d/sdL7 primary in a wide L+T binary, we find similar Teff sources have similar P-T profiles with metallicity differences impacting the relative offset between their P-T profiles in the photosphere. We also find that for near-infrared spectra, when the SNR is $\gtrsim80$ we are in a regime where model uncertainties dominate over data measurement uncertainties. As such, SNR does not play a role in the retrieval's ability to distinguish between a cloud-free and cloudless model, but may impact the confidence of the retrieved parameters. Lastly, we also discuss how to break cloud model degeneracies and the impact of extraneous gases in a retrieval model. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.02754v1-abstract-full').style.display = 'none'; document.getElementById('2209.02754v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 3 figures, 7 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.14317">arXiv:2208.14317</a> <span> [<a href="https://arxiv.org/pdf/2208.14317">pdf</a>, <a href="https://arxiv.org/format/2208.14317">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac8dfb">10.3847/1538-4357/ac8dfb <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Probing the Extent of Vertical Mixing in Brown Dwarf Atmospheres with Disequilibrium Chemistry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Mukherjee%2C+S">Sagnick Mukherjee</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Batalha%2C+N+E">Natasha E. Batalha</a>, <a href="/search/?searchtype=author&query=Karalidi%2C+T">Theodora Karalidi</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Miles%2C+B+E">Brittany E. Miles</a>, <a href="/search/?searchtype=author&query=Skemer%2C+A+J+I">Andrew J. I. Skemer</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2208.14317v1-abstract-short" style="display: inline;"> Evidence of disequilibrium chemistry due to vertical mixing in the atmospheres of many T and Y-dwarfs has been inferred due to enhanced mixing ratios of CO and reduced NH$_3$. Atmospheric models of planets and brown dwarfs typically parameterize this vertical mixing phenomenon with the vertical eddy diffusion coefficient, $K_{\rm zz}$. While $K_{\rm zz}$ can perhaps be approximated in the convecti… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.14317v1-abstract-full').style.display = 'inline'; document.getElementById('2208.14317v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.14317v1-abstract-full" style="display: none;"> Evidence of disequilibrium chemistry due to vertical mixing in the atmospheres of many T and Y-dwarfs has been inferred due to enhanced mixing ratios of CO and reduced NH$_3$. Atmospheric models of planets and brown dwarfs typically parameterize this vertical mixing phenomenon with the vertical eddy diffusion coefficient, $K_{\rm zz}$. While $K_{\rm zz}$ can perhaps be approximated in the convective regions in the atmosphere with mixing length theory, in radiative regions the strength of vertical mixing is uncertain by many orders of magnitude. With a new grid of self-consistent 1D model atmospheres from $T_{\rm eff}$ of 400 - 1000 K, computed with a new radiative-convective equilibrium python code PICASO 3.0, we aim to assess how molecular abundances and corresponding spectra can be used as a probe of depth-dependent $K_{\rm zz}$. At a given surface gravity, we find non-monotonic behavior in the CO abundance as a function of $T_{\rm eff}$, as chemical abundances are sometimes quenched in either of two potential atmospheric convective zones, or quenched in either of two possible radiative zones. The temperature structure and chemical quenching behavior also changes with gravity. We compare our models with available near-infrared and M-band spectroscopy of several T and Y-dwarfs and assess their atmospheric vertical mixing profiles. We also compare to color-magnitude diagrams and make predictions for JWST spectra. This work yields new constraints, and points the way to significant future gains, in determining $K_{\rm zz}$, a fundamental atmospheric parameter in substellar atmospheres, with significant implications for chemistry and cloud modeling. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.14317v1-abstract-full').style.display = 'none'; document.getElementById('2208.14317v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for Publication in The Astrophysical Journal, 31 Pages, 22 Figures. The model grid will be released via Zenodo</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.11824">arXiv:2110.11824</a> <span> [<a href="https://arxiv.org/pdf/2110.11824">pdf</a>, <a href="https://arxiv.org/format/2110.11824">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac3140">10.3847/1538-4357/ac3140 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Sonora Substellar Atmosphere Models. II. Cholla: A Grid of Cloud-free, Solar Metallicity Models in Chemical Disequilibrium for the JWST Era </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Karalidi%2C+T">Theodora Karalidi</a>, <a href="/search/?searchtype=author&query=Marley%2C+M">Mark Marley</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Morley%2C+C">Caroline Morley</a>, <a href="/search/?searchtype=author&query=Saumon%2C+D">Didier Saumon</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.11824v1-abstract-short" style="display: inline;"> Exoplanet and brown dwarf atmospheres commonly show signs of disequilibrium chemistry. In the James Webb Space Telescope era high resolution spectra of directly imaged exoplanets will allow the characterization of their atmospheres in more detail, and allow systematic tests for the presence of chemical species that deviate from thermochemical equilibrium in these atmospheres. Constraining the pres… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.11824v1-abstract-full').style.display = 'inline'; document.getElementById('2110.11824v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.11824v1-abstract-full" style="display: none;"> Exoplanet and brown dwarf atmospheres commonly show signs of disequilibrium chemistry. In the James Webb Space Telescope era high resolution spectra of directly imaged exoplanets will allow the characterization of their atmospheres in more detail, and allow systematic tests for the presence of chemical species that deviate from thermochemical equilibrium in these atmospheres. Constraining the presence of disequilibrium chemistry in these atmospheres as a function of parameters such as their effective temperature and surface gravity will allow us to place better constrains in the physics governing these atmospheres. This paper is part of a series of works presenting the Sonora grid of atmosphere models (Marley et al 2021, Morley et al in prep.). In this paper we present a grid of cloud-free, solar metallicity atmospheres for brown dwarfs and wide separation giant planets with key molecular species such as CH4, H2O, CO and NH3 in disequilibrium. Our grid covers atmospheres with Teff~[500 K,1300 K], logg~[3.0,5.5] (cgs) and an eddy diffusion parameter of logKzz=2, 4 and 7 (cgs). We study the effect of different parameters within the grid on the temperature and composition profiles of our atmospheres. We discuss their effect on the near-infrared colors of our model atmospheres and the detectability of CH4, H2O, CO and NH3 using the JWST. We compare our models against existing MKO and Spitzer observations of brown dwarfs and verify the importance of disequilibrium chemistry for T dwarf atmospheres. Finally, we discuss how our models can help constrain the vertical structure and chemical composition of these atmospheres. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.11824v1-abstract-full').style.display = 'none'; document.getElementById('2110.11824v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted to ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.11000">arXiv:2109.11000</a> <span> [<a href="https://arxiv.org/pdf/2109.11000">pdf</a>, <a href="https://arxiv.org/format/2109.11000">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac294e">10.3847/1538-4357/ac294e <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The first retrieval of a substellar subdwarf: A cloud-free SDSS J125637.13-022452.4 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Gonzales%2C+E+C">Eileen C. Gonzales</a>, <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J+K">Jacqueline K. Faherty</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Marley%2C+M">Mark Marley</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a>, <a href="/search/?searchtype=author&query=Lewis%2C+N+K">Nikole K. Lewis</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2109.11000v1-abstract-short" style="display: inline;"> We present the first retrieval analysis of a substellar subdwarf, SDSS J125637.13-022452.4 (SDSS J1256-0224), using the Brewster retrieval code base. We find SDSS J1256-0224 is best fit by a cloud-free model with an ion (neutral H, H-, and electron) abundance corresponding to ion [Fe/H]=-1.5. However, this model is indistinguishable from a cloud-free model with ion [Fe/H]=-2.0 and a cloud-free mod… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.11000v1-abstract-full').style.display = 'inline'; document.getElementById('2109.11000v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.11000v1-abstract-full" style="display: none;"> We present the first retrieval analysis of a substellar subdwarf, SDSS J125637.13-022452.4 (SDSS J1256-0224), using the Brewster retrieval code base. We find SDSS J1256-0224 is best fit by a cloud-free model with an ion (neutral H, H-, and electron) abundance corresponding to ion [Fe/H]=-1.5. However, this model is indistinguishable from a cloud-free model with ion [Fe/H]=-2.0 and a cloud-free model with ion Fe/H]=-1.5 assuming a subsolar carbon-to-oxygen ratio. We are able to constrain abundances for water, FeH, and CrH, with an inability to constrain any carbon-bearing species likely due to the low-metallicity of SDSS J1256-0224. We also present an updated spectral energy distribution (SED) and semi-empirical fundamental parameters. Our retrieval- and SED-based fundamental parameters agree with the Baraffe low-metallicity evolutionary models. From examining our "rejected" models (those with $螖$BIC>45), we find that we are able to retrieve gas abundances consistent with those of our best-fitting model. We find the cloud in these poorer fitting "cloudy" models is either pushed to the bottom of the atmosphere or made optically thin. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.11000v1-abstract-full').style.display = 'none'; document.getElementById('2109.11000v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 5 figures. arXiv admin note: text overlap with arXiv:2010.01224</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.07434">arXiv:2107.07434</a> <span> [<a href="https://arxiv.org/pdf/2107.07434">pdf</a>, <a href="https://arxiv.org/format/2107.07434">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac141d">10.3847/1538-4357/ac141d <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Sonora Brown Dwarf Atmosphere and Evolution Models I. Model Description and Application to Cloudless Atmospheres in Rainout Chemical Equilibrium </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Saumon%2C+D">Didier Saumon</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a>, <a href="/search/?searchtype=author&query=Morley%2C+C">Caroline Morley</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Seay%2C+C">Christopher Seay</a>, <a href="/search/?searchtype=author&query=Smith%2C+A+J+R+W">Adam J. R. W. Smith</a>, <a href="/search/?searchtype=author&query=Teal%2C+D+J">D. J. Teal</a>, <a href="/search/?searchtype=author&query=Wang%2C+R">Ruoyan Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.07434v1-abstract-short" style="display: inline;"> We present a new generation of substellar atmosphere and evolution models, appropriate for application to studies of L, T, and Y-type brown dwarfs and self-luminous extrasolar planets. The atmosphere models describe the expected temperature-pressure profiles and emergent spectra of atmospheres in radiative-convective equilibrium with effective temperatures and gravities within the ranges… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.07434v1-abstract-full').style.display = 'inline'; document.getElementById('2107.07434v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.07434v1-abstract-full" style="display: none;"> We present a new generation of substellar atmosphere and evolution models, appropriate for application to studies of L, T, and Y-type brown dwarfs and self-luminous extrasolar planets. The atmosphere models describe the expected temperature-pressure profiles and emergent spectra of atmospheres in radiative-convective equilibrium with effective temperatures and gravities within the ranges $200\le T_{\rm eff}\le2400\,\rm K$ and $2.5\le \log g \le 5.5$. These ranges encompass masses from about 0.5 to 85 Jupiter masses for a set of metallicities ($[{\rm M/H}] = -0.5$ to $+0.5$), C/O ratios (from 0.5 to 1.5 times that of solar), and ages. The evolution tables describe the cooling of these substellar objects through time. These models expand the diversity of model atmospheres currently available, notably to cooler effective temperatures and greater ranges in C/O. Notable improvements from past such models include updated opacities and atmospheric chemistry. Here we describe our modeling approach and present our initial tranche of models for cloudless, chemical equilibrium atmospheres. We compare the modeled spectra, photometry, and evolution to various datasets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.07434v1-abstract-full').style.display = 'none'; document.getElementById('2107.07434v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">27 pages, 16 figures, accepted for Astrophysical Journal. Models available at https://doi.org/10.5281/zenodo.5063476</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.00781">arXiv:2106.00781</a> <span> [<a href="https://arxiv.org/pdf/2106.00781">pdf</a>, <a href="https://arxiv.org/format/2106.00781">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac0a7d">10.3847/1538-4357/ac0a7d <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Following the Lithium: Tracing Li-bearing Molecules Across Age, Mass, and Gravity in Brown Dwarfs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Gharib-Nezhad%2C+E">Ehsan Gharib-Nezhad</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Batalha%2C+N+E">Natasha E. Batalha</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R+S">Richard S. Freedman</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R+E">Roxana E. Lupu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.00781v1-abstract-short" style="display: inline;"> Lithium is an important element for the understanding of ultracool dwarfs because it is lost to fusion at masses above $\sim 68\, M_{\rm J}$. Hence, the presence or absence of atomic Li has served as an indicator of the nearby H-burning boundary at about $75\,M_{\rm J}$ between brown-dwarfs and very low-mass stars. Historically the "Lithium test", a search for the presence and strength of the Li l… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.00781v1-abstract-full').style.display = 'inline'; document.getElementById('2106.00781v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.00781v1-abstract-full" style="display: none;"> Lithium is an important element for the understanding of ultracool dwarfs because it is lost to fusion at masses above $\sim 68\, M_{\rm J}$. Hence, the presence or absence of atomic Li has served as an indicator of the nearby H-burning boundary at about $75\,M_{\rm J}$ between brown-dwarfs and very low-mass stars. Historically the "Lithium test", a search for the presence and strength of the Li line at 670.8 nm, has been a marker if an object has a substellar mass with stellar-like spectral energy distribution (e.g., a late-type M dwarf). While the Li test could in principle also be used to distinguish masses of later-type L-T dwarfs, Li is predominantly no longer found as an atomic gas, but rather a molecular species such as LiH, LiF, LiOH, and LiCl in their cooler atmospheres. L- and T-type brown dwarfs are also quite faint at 670 nm and thus challenging targets for high resolution spectroscopy. But only recently have experimental molecular line lists become available for the molecular Li species, allowing molecular Li mass discrimination. In this study, we generated the latest opacity of each of these Li-bearing molecules and performed thermochemical equilibrium atmospheric composition calculation of the abundance of these molecules. Finally, we computed thermal emission spectra for a series of radiative-convective equilibrium models of cloudy and cloudless brown dwarf atmospheres (with $T_{\rm eff}=$ 500--2400~K, and $\log g$=4.0, 4.5, 5.0) to understand where the presence or absence of atmospheric lithium-bearing species is most easily detected as a function of brown dwarf mass and age. After atomic Li, the best spectral signatures were found to be LiF at $10.5-12.5$~\micron and LiCl at $14.5-18.5$ $\micron$. LiH also shows a narrow feature at $\sim 9.38$ $\micron$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.00781v1-abstract-full').style.display = 'none'; document.getElementById('2106.00781v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 7 figures, 1 table, In final revision at ApJ. Comments welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.04268">arXiv:2105.04268</a> <span> [<a href="https://arxiv.org/pdf/2105.04268">pdf</a>, <a href="https://arxiv.org/format/2105.04268">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stab1361">10.1093/mnras/stab1361 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cloud busting: enstatite and quartz clouds in the atmosphere of 2M2224-0158 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J+K">Jacqueline K. Faherty</a>, <a href="/search/?searchtype=author&query=Gonzales%2C+E+C">Eileen C. Gonzales</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Gaarn%2C+J">Josefine Gaarn</a>, <a href="/search/?searchtype=author&query=Bieger%2C+M+F">Michelle Fabienne Bieger</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a>, <a href="/search/?searchtype=author&query=Saumon%2C+D">Didier Saumon</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.04268v1-abstract-short" style="display: inline;"> We present the most detailed data-driven exploration of cloud opacity in a substellar object to-date. We have tested over 60 combinations of cloud composition and structure, particle size distribution, scattering model, and gas phase composition assumptions against archival $1-15 {\rm 渭m}$ spectroscopy for the unusually red L4.5~dwarf 2MASSW~J2224438-015852 using the Brewster retrieval framework.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.04268v1-abstract-full').style.display = 'inline'; document.getElementById('2105.04268v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.04268v1-abstract-full" style="display: none;"> We present the most detailed data-driven exploration of cloud opacity in a substellar object to-date. We have tested over 60 combinations of cloud composition and structure, particle size distribution, scattering model, and gas phase composition assumptions against archival $1-15 {\rm 渭m}$ spectroscopy for the unusually red L4.5~dwarf 2MASSW~J2224438-015852 using the Brewster retrieval framework. We find that, within our framework, a model that includes enstatite and quartz cloud layers at shallow pressures, combined with a deep iron cloud deck fits the data best. This models assumes a Hansen distribution for particle sizes for each cloud, and Mie scattering. We retrieved particle effective radii of $\log_{10} a {\rm (渭m)} = -1.41^{+0.18}_{-0.17}$ for enstatite, $-0.44^{+0.04}_{-0.20}$ for quartz, and $-0.77^{+0.05}_{-0.06}$ for iron. Our inferred cloud column densities suggest ${\rm (Mg/Si)} = 0.69^{+0.06}_{-0.08}$ if there are no other sinks for magnesium or silicon. Models that include forsterite alongside, or in place of, these cloud species are strongly rejected in favour of the above combination. We estimate a radius of $0.75 \pm 0.02$ Rjup, which is considerably smaller than predicted by evolutionary models for a field age object with the luminosity of 2M2224-0158. Models which assume vertically constant gas fractions are consistently preferred over models that assume thermochemical equilibrium. From our retrieved gas fractions we infer ${\rm [M/H]} = +0.38^{+0.07}_{-0.06}$ and ${\rm C/O} = 0.83^{+0.06}_{-0.07}$. Both these values are towards the upper end of the stellar distribution in the Solar neighbourhood, and are mutually consistent in this context. A composition toward the extremes of the local distribution is consistent with this target being an outlier in the ultracool dwarf population. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.04268v1-abstract-full').style.display = 'none'; document.getElementById('2105.04268v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 10 figures, MNRAS accepted</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2010.01224">arXiv:2010.01224</a> <span> [<a href="https://arxiv.org/pdf/2010.01224">pdf</a>, <a href="https://arxiv.org/format/2010.01224">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/abbee2">10.3847/1538-4357/abbee2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Retrieval of SDSS J1416+1348AB </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Gonzales%2C+E">Eileen Gonzales</a>, <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J">Jackie Faherty</a>, <a href="/search/?searchtype=author&query=Cleary%2C+C">Colleen Cleary</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Marley%2C+M">Mark Marley</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2010.01224v1-abstract-short" style="display: inline;"> We present the distance-calibrated spectral energy distribution (SED) of the d/sdL7 SDSS J14162408+1348263A (J1416A) and an updated SED for SDSS J14162408+1348263B (J1416B). We also present the first retrieval analysis of J1416A using the Brewster retrieval code base and the second retrieval of J1416B. We find that the primary is best fit by a non-grey cloud opacity with a power-law wavelength dep… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.01224v1-abstract-full').style.display = 'inline'; document.getElementById('2010.01224v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2010.01224v1-abstract-full" style="display: none;"> We present the distance-calibrated spectral energy distribution (SED) of the d/sdL7 SDSS J14162408+1348263A (J1416A) and an updated SED for SDSS J14162408+1348263B (J1416B). We also present the first retrieval analysis of J1416A using the Brewster retrieval code base and the second retrieval of J1416B. We find that the primary is best fit by a non-grey cloud opacity with a power-law wavelength dependence, but is indistinguishable between the type of cloud parameterization. J1416B is best fit by a cloud-free model, consistent with the results from Line et al. (2017). Most fundamental parameters derived via SEDs and retrievals are consistent within 1 sigma for both J1416A and J1416B. The exceptions include the radius of J1416A, where the retrieved radius is smaller than the evolutionary model-based radius from the SED for the deck cloud model, and the bolometric luminosity which is consistent within 2.5 sigma for both cloud models. The pair's metallicity and Carbon-to-Oxygen (C/O) ratio point towards formation and evolution as a system. By comparing the retrieved alkali abundances while using two opacity models, we are able to evaluate how the opacities behave for the L and T dwarf. Lastly, we find that relatively small changes in composition can drive major observable differences for lower temperature objects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.01224v1-abstract-full').style.display = 'none'; document.getElementById('2010.01224v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">40 pages, 25 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2010.00146">arXiv:2010.00146</a> <span> [<a href="https://arxiv.org/pdf/2010.00146">pdf</a>, <a href="https://arxiv.org/format/2010.00146">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-3881/abc5bd">10.3847/1538-3881/abc5bd <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Beyond Equilibrium Temperature: How the Atmosphere/Interior Connection Affects the Onset of Methane, Ammonia, and Clouds in Warm Transiting Giant Planets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Hood%2C+C+E">Callie E. Hood</a>, <a href="/search/?searchtype=author&query=Line%2C+M+R">Michael R. Line</a>, <a href="/search/?searchtype=author&query=Thorngren%2C+D+P">Daniel P. Thorngren</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R+S">Richard S. Freedman</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2010.00146v2-abstract-short" style="display: inline;"> The atmospheric pressure-temperature profiles for transiting giant planets cross a range of chemical transitions. Here we show that the particular shape of these irradiated profiles for warm giant planets below 1300 K lead to striking differences in the behavior of non-equilibrium chemistry compared to brown dwarfs of similar temperatures. Our particular focus is H$_2$O, CO, CH$_4$, CO$_2$, and NH… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.00146v2-abstract-full').style.display = 'inline'; document.getElementById('2010.00146v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2010.00146v2-abstract-full" style="display: none;"> The atmospheric pressure-temperature profiles for transiting giant planets cross a range of chemical transitions. Here we show that the particular shape of these irradiated profiles for warm giant planets below 1300 K lead to striking differences in the behavior of non-equilibrium chemistry compared to brown dwarfs of similar temperatures. Our particular focus is H$_2$O, CO, CH$_4$, CO$_2$, and NH$_3$ in Jupiter- and Neptune-class planets. We show the cooling history of a planet, which depends most significantly on planetary mass and age, can have a dominant effect on abundances in the visible atmosphere, often swamping trends one might expect based on Teq alone. The onset of detectable CH$_4$ in spectra can be delayed to lower Teq for some planets compared to equilibrium, or pushed to higher Teq. The detectability of NH$_3$ is typically enhanced compared to equilibrium expectations, which is opposite to the brown dwarf case. We find that both CH$_4$ and NH$_3$ can become detectable at around the same Teq (at Teq values that vary with mass and metallicity) whereas these "onset" temperatures are widely spaced for brown dwarfs. We suggest observational strategies to search for atmospheric trends and stress that non-equilibrium chemistry and clouds can serve as probes of atmospheric physics. As examples of atmospheric complexity, we assess three Neptune-class planets GJ 436b, GJ 3470b, and WASP-107, all around Teq=700 K. Tidal heating due to eccentricity damping in all three planets heats the deep atmosphere by thousands of degrees, and may explain the absence of CH$_4$ in these cool atmospheres. Atmospheric abundances must be interpreted in the context of physical characteristics of the planet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.00146v2-abstract-full').style.display = 'none'; document.getElementById('2010.00146v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to AJ. No additional significant changes</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2004.10770">arXiv:2004.10770</a> <span> [<a href="https://arxiv.org/pdf/2004.10770">pdf</a>, <a href="https://arxiv.org/format/2004.10770">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-3881/ab9114">10.3847/1538-3881/ab9114 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observations of Disequilibrium CO Chemistry in the Coldest Brown Dwarfs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Miles%2C+B+E">Brittany E. Miles</a>, <a href="/search/?searchtype=author&query=Skemer%2C+A+J+I">Andrew J. I. Skemer</a>, <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Allers%2C+K+N">Katelyn N. Allers</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J+K">Jacqueline K. Faherty</a>, <a href="/search/?searchtype=author&query=Geballe%2C+T+R">Thomas R. Geballe</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Schneider%2C+A+C">Adam C. Schneider</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R+S">Richard S. Freedman</a>, <a href="/search/?searchtype=author&query=Bjoraker%2C+G+L">Gordon L. Bjoraker</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2004.10770v2-abstract-short" style="display: inline;"> Cold brown dwarfs are excellent analogs of widely separated, gas giant exoplanets, and provide insight into the potential atmospheric chemistry and physics we may encounter in objects discovered by future direct imaging surveys. We present a low resolution R $\sim$ 300 $M$-band spectroscopic sequence of seven brown dwarfs with effective temperatures between 750 K and 250 K along with Jupiter. Thes… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2004.10770v2-abstract-full').style.display = 'inline'; document.getElementById('2004.10770v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2004.10770v2-abstract-full" style="display: none;"> Cold brown dwarfs are excellent analogs of widely separated, gas giant exoplanets, and provide insight into the potential atmospheric chemistry and physics we may encounter in objects discovered by future direct imaging surveys. We present a low resolution R $\sim$ 300 $M$-band spectroscopic sequence of seven brown dwarfs with effective temperatures between 750 K and 250 K along with Jupiter. These spectra reveal disequilibrium abundances of carbon monoxide (CO) produced by atmospheric quenching. We use the eddy diffusion coefficient (K$_{zz}$) to estimate the strength of vertical mixing in each object. The K$_{zz}$ values of cooler gaseous objects are close to their theoretical maximum and warmer objects show weaker mixing, likely due to less efficient convective mixing in primarily radiative layers. The CO-derived K$_{zz}$ values imply that disequilibrium phosphine (PH$_{3}$) should be easily observable in all of the brown dwarfs, but none as yet show any evidence for PH$_{3}$ absorption. We find that ammonia is relatively insensitive to atmospheric quenching at these effective temperatures. We are able to improve the fit to WISE 0855's $M$-band spectrum by including both CO and water clouds in the atmospheric model. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2004.10770v2-abstract-full').style.display = 'none'; document.getElementById('2004.10770v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 April, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 April, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to the Astronomical Journal. 24 Pages, 16 Figures, 4 Tables. take care</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1903.09322">arXiv:1903.09322</a> <span> [<a href="https://arxiv.org/pdf/1903.09322">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> </div> <p class="title is-5 mathjax"> Imaging Cool Giant Planets in Reflected Light: Science Investigations and Synergy with Habitable Planets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Marley%2C+M">Mark Marley</a>, <a href="/search/?searchtype=author&query=Lewis%2C+N">Nikole Lewis</a>, <a href="/search/?searchtype=author&query=Arney%2C+G">Giada Arney</a>, <a href="/search/?searchtype=author&query=Bailey%2C+V">Vanessa Bailey</a>, <a href="/search/?searchtype=author&query=Batalha%2C+N">Natasha Batalha</a>, <a href="/search/?searchtype=author&query=Beichman%2C+C">Charles Beichman</a>, <a href="/search/?searchtype=author&query=Benneke%2C+B">Bj枚rn Benneke</a>, <a href="/search/?searchtype=author&query=Blecic%2C+J">Jasmina Blecic</a>, <a href="/search/?searchtype=author&query=Cahoy%2C+K">Kerri Cahoy</a>, <a href="/search/?searchtype=author&query=Chilcote%2C+J">Jeffrey Chilcote</a>, <a href="/search/?searchtype=author&query=Domagal-Goldman%2C+S">Shawn Domagal-Goldman</a>, <a href="/search/?searchtype=author&query=Dressing%2C+C">Courtney Dressing</a>, <a href="/search/?searchtype=author&query=Fitzgerald%2C+M">Michael Fitzgerald</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J">Jonathan Fortney</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a>, <a href="/search/?searchtype=author&query=Gelino%2C+D">Dawn Gelino</a>, <a href="/search/?searchtype=author&query=Gizis%2C+J">John Gizis</a>, <a href="/search/?searchtype=author&query=Guyon%2C+O">Olivier Guyon</a>, <a href="/search/?searchtype=author&query=Greene%2C+T">Thomas Greene</a>, <a href="/search/?searchtype=author&query=Hammel%2C+H">Heidi Hammel</a>, <a href="/search/?searchtype=author&query=Hasegawa%2C+Y">Yasuhiro Hasegawa</a>, <a href="/search/?searchtype=author&query=Jovanovic%2C+N">Nemanja Jovanovic</a>, <a href="/search/?searchtype=author&query=Konopacky%2C+Q">Quinn Konopacky</a>, <a href="/search/?searchtype=author&query=Kopparapu%2C+R">Ravi Kopparapu</a>, <a href="/search/?searchtype=author&query=Liu%2C+M">Michael Liu</a> , et al. (16 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1903.09322v2-abstract-short" style="display: inline;"> Planned astronomical observatories of the 2020s will be capable of obtaining reflected light photometry and spectroscopy of cool extrasolar giant planets. Here we explain that such data are valuable both for understanding the origin and evolution of giant planets as a whole and for preparing for the interpretation of similar datasets from potentially habitable extrasolar terrestrial planets in the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1903.09322v2-abstract-full').style.display = 'inline'; document.getElementById('1903.09322v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1903.09322v2-abstract-full" style="display: none;"> Planned astronomical observatories of the 2020s will be capable of obtaining reflected light photometry and spectroscopy of cool extrasolar giant planets. Here we explain that such data are valuable both for understanding the origin and evolution of giant planets as a whole and for preparing for the interpretation of similar datasets from potentially habitable extrasolar terrestrial planets in the decades to follow. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1903.09322v2-abstract-full').style.display = 'none'; document.getElementById('1903.09322v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 March, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 March, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Science white paper submitted to the Astro 2020 Decadal Survey on Astronomy and Astrophysics. Replace version to fix typo in co-signer name and add figure credits</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1805.00096">arXiv:1805.00096</a> <span> [<a href="https://arxiv.org/pdf/1805.00096">pdf</a>, <a href="https://arxiv.org/format/1805.00096">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201833059">10.1051/0004-6361/201833059 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> From thermal dissociation to condensation in the atmospheres of ultra hot Jupiters: WASP-121b in context </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Parmentier%2C+V">Vivien Parmentier</a>, <a href="/search/?searchtype=author&query=Line%2C+M+R">Mike R. Line</a>, <a href="/search/?searchtype=author&query=Bean%2C+J+L">Jacob L. Bean</a>, <a href="/search/?searchtype=author&query=Mansfield%2C+M">Megan Mansfield</a>, <a href="/search/?searchtype=author&query=Kreidberg%2C+L">Laura Kreidberg</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Desert%2C+J">Jean-Michel Desert</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Deleuil%2C+M">Magalie Deleuil</a>, <a href="/search/?searchtype=author&query=Arcangeli%2C+J">Jacob Arcangeli</a>, <a href="/search/?searchtype=author&query=Showman%2C+A+P">Adam P. Showman</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1805.00096v2-abstract-short" style="display: inline;"> A new class of exoplanets has emerged: the ultra hot Jupiters, the hottest close-in gas giants. Most of them have weaker than expected spectral features in the $1.1-1.7渭m$ bandpass probed by HST/WFC3 but stronger spectral features at longer wavelengths probed by Spitzer. This led previous authors to puzzling conclusions about the thermal structures and chemical abundances of these planets. Using t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.00096v2-abstract-full').style.display = 'inline'; document.getElementById('1805.00096v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1805.00096v2-abstract-full" style="display: none;"> A new class of exoplanets has emerged: the ultra hot Jupiters, the hottest close-in gas giants. Most of them have weaker than expected spectral features in the $1.1-1.7渭m$ bandpass probed by HST/WFC3 but stronger spectral features at longer wavelengths probed by Spitzer. This led previous authors to puzzling conclusions about the thermal structures and chemical abundances of these planets. Using the SPARC/MITgcm, we investigate how thermal dissociation, ionization, H$^-$ opacity and clouds shape the thermal structures and spectral properties of ultra hot Jupiters with a special focus on WASP-121b. We expand our findings to the whole population of ultra hot Jupiters through analytical quantification of the thermal dissociation and its influence on the strength of spectral features. We predict that most molecules are thermally dissociated and alkalies are ionized in the dayside photospheres of ultra hot Jupiters. This includes H$_{\rm 2}$O, TiO, VO, and H$_{\rm 2}$ but not CO, which has a stronger molecular bond. The vertical molecular gradient created by the dissociation significantly weakens the spectral features from water while the $4.5渭m$ CO feature remain unchanged. The water band in the HST/WFC3 bandpass is further weakened by H$^-$ continuum opacity. Molecules are expected to recombine before reaching the limb, leading to order of magnitude variations of the chemical composition and cloud coverage between the limb and the dayside. Overall, molecular dissociation provides a qualitative understanding of the lack of strong spectral feature of water in the $1-2渭m$ bandpass observed in most ultra hot Jupiters. Quantitatively, however, our model does not provide a satisfactory match to the WASP-121b emission spectrum. Together with WASP-33b and Kepler-33Ab, they seem the outliers among the population of ultra hot Jupiters in need of a more thorough understanding. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.00096v2-abstract-full').style.display = 'none'; document.getElementById('1805.00096v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 August, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 April, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 617, A110 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1804.07771">arXiv:1804.07771</a> <span> [<a href="https://arxiv.org/pdf/1804.07771">pdf</a>, <a href="https://arxiv.org/format/1804.07771">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/aabe8b">10.3847/1538-4357/aabe8b <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> An L Band Spectrum of the Coldest Brown Dwarf </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Skemer%2C+A+J">Andrew J. Skemer</a>, <a href="/search/?searchtype=author&query=Allers%2C+K+N">Katelyn N. Allers</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark. S. Marley</a>, <a href="/search/?searchtype=author&query=Faherty%2C+J+K">Jacqueline K. Faherty</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Beiler%2C+S+A">Samuel A. Beiler</a>, <a href="/search/?searchtype=author&query=Miles%2C+B+E">Brittany E. Miles</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R+S">Richard S. Freedman</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Geballe%2C+T+R">Thomas R. Geballe</a>, <a href="/search/?searchtype=author&query=Bjoraker%2C+G+L">Gordon L. Bjoraker</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1804.07771v1-abstract-short" style="display: inline;"> The coldest brown dwarf, WISE 0855, is the closest known planetary-mass, free-floating object and has a temperature nearly as cold as the solar system gas giants. Like Jupiter, it is predicted to have an atmosphere rich in methane, water, and ammonia, with clouds of volatile ices. WISE 0855 is faint at near-infrared wavelengths and emits almost all its energy in the mid-infrared. Skemer et al. 201… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1804.07771v1-abstract-full').style.display = 'inline'; document.getElementById('1804.07771v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1804.07771v1-abstract-full" style="display: none;"> The coldest brown dwarf, WISE 0855, is the closest known planetary-mass, free-floating object and has a temperature nearly as cold as the solar system gas giants. Like Jupiter, it is predicted to have an atmosphere rich in methane, water, and ammonia, with clouds of volatile ices. WISE 0855 is faint at near-infrared wavelengths and emits almost all its energy in the mid-infrared. Skemer et al. 2016 presented a spectrum of WISE 0855 from 4.5-5.1 micron (M band), revealing water vapor features. Here, we present a spectrum of WISE 0855 in L band, from 3.4-4.14 micron. We present a set of atmosphere models that include a range of compositions (metallicities and C/O ratios) and water ice clouds. Methane absorption is clearly present in the spectrum. The mid-infrared color can be better matched with a methane abundance that is depleted relative to solar abundance. We find that there is evidence for water ice clouds in the M band spectrum, and we find a lack of phosphine spectral features in both the L and M band spectra. We suggest that a deep continuum opacity source may be obscuring the near-infrared flux, possibly a deep phosphorous-bearing cloud, ammonium dihyrogen phosphate. Observations of WISE 0855 provide critical constraints for cold planetary atmospheres, bridging the temperature range between the long-studied solar system planets and accessible exoplanets. JWST will soon revolutionize our understanding of cold brown dwarfs with high-precision spectroscopy across the infrared, allowing us to study their compositions and cloud properties, and to infer their atmospheric dynamics and formation processes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1804.07771v1-abstract-full').style.display = 'none'; document.getElementById('1804.07771v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 April, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 21 figures. Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1701.01257">arXiv:1701.01257</a> <span> [<a href="https://arxiv.org/pdf/1701.01257">pdf</a>, <a href="https://arxiv.org/format/1701.01257">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stx1246">10.1093/mnras/stx1246 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Retrieval of atmospheric properties of cloudy L dwarfs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Burningham%2C+B">Ben Burningham</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Line%2C+M+R">Michael R. Line</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Saumon%2C+D">Didier Saumon</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1701.01257v2-abstract-short" style="display: inline;"> We present the first results from applying the spectral inversion technique in the cloudy L dwarf regime. Our new framework provides a flexible approach to modelling cloud opacity which can be built incrementally as the data requires, and improves upon previous retrieval experiments in the brown dwarf regime by allowing for scattering in two stream radiative transfer. Our first application of the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.01257v2-abstract-full').style.display = 'inline'; document.getElementById('1701.01257v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1701.01257v2-abstract-full" style="display: none;"> We present the first results from applying the spectral inversion technique in the cloudy L dwarf regime. Our new framework provides a flexible approach to modelling cloud opacity which can be built incrementally as the data requires, and improves upon previous retrieval experiments in the brown dwarf regime by allowing for scattering in two stream radiative transfer. Our first application of the tool to two mid-L dwarfs is able to reproduce their near-infrared spectra far more closely than grid models. Our retrieved thermal, chemical, and cloud profiles allow us to estimate $T_{\rm eff} = 1796^{+23}_{-25}$ K and $\log g = 5.21^{+0.05}_{-0.08}$ for 2MASS J05002100+0330501 and for 2MASSW J2224438-015852 we find $T_{\rm eff} = 1723^{+18}_{-19}$ K and $\log g = 5.31^{+0.04}_{-0.08}$, in close agreement with previous empirical estimates. Our best model for both objects includes an optically thick cloud deck which passes $蟿_{cloud} \geq 1$ (looking down) at a pressure of around 5 bar. The temperature at this pressure is too high for silicate species to condense, and we argue that corundum and/or iron clouds are responsible for this cloud opacity. Our retrieved profiles are cooler at depth, and warmer at altitude than the forward grid models that we compare, and we argue that some form of heating mechanism may be at work in the upper atmospheres of these L dwarfs. We also identify anomalously high CO abundance in both targets, which does not correlate with the warmth of our upper atmospheres or our choice of cloud model, and find similarly anomalous alkali abundance for one of our targets. These anomalies may reflect unrecognised shortcomings in our retrieval model, or inaccuracies in our gas phase opacities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.01257v2-abstract-full').style.display = 'none'; document.getElementById('1701.01257v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 May, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 January, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in MNRAS. Changes in review: additional validation against T dwarf test case, posteriors for cloud free retrievals and contribution functions added to Appendix. Also, entire investigation re-run with new UCL H2O opacities, with minimal impact on results</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1610.03325">arXiv:1610.03325</a> <span> [<a href="https://arxiv.org/pdf/1610.03325">pdf</a>, <a href="https://arxiv.org/format/1610.03325">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stw2639">10.1093/mnras/stw2639 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High temperature condensate clouds in super-hot Jupiter atmospheres </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Wakeford%2C+H+R">Hannah R. Wakeford</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Lewis%2C+N+K">Nikole K. Lewis</a>, <a href="/search/?searchtype=author&query=Kataria%2C+T">Tiffany Kataria</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Mandell%2C+A+M">Avi M. Mandell</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1610.03325v1-abstract-short" style="display: inline;"> Deciphering the role of clouds is central to our understanding of exoplanet atmospheres, as they have a direct impact on the temperature and pressure structure, and observational properties of the planet. Super-hot Jupiters occupy a temperature regime similar to low mass M-dwarfs, where minimal cloud condensation is expected. However, observations of exoplanets such as WASP-12b (Teq ~ 2500 K) resu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.03325v1-abstract-full').style.display = 'inline'; document.getElementById('1610.03325v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1610.03325v1-abstract-full" style="display: none;"> Deciphering the role of clouds is central to our understanding of exoplanet atmospheres, as they have a direct impact on the temperature and pressure structure, and observational properties of the planet. Super-hot Jupiters occupy a temperature regime similar to low mass M-dwarfs, where minimal cloud condensation is expected. However, observations of exoplanets such as WASP-12b (Teq ~ 2500 K) result in a transmission spectrum indicative of a cloudy atmosphere. We re-examine the temperature and pressure space occupied by these super-hot Jupiter atmospheres, to explore the role of the initial Al- and Ti-bearing condensates as the main source of cloud material. Due to the high temperatures a majority of the more common refractory material is not depleted into deeper layers and would remain in the vapor phase. The lack of depletion into deeper layers means that these materials with relatively low cloud masses can become significant absorbers in the upper atmosphere. We provide condensation curves for the initial Al- and Ti-bearing condensates that may be used to provide quantitative estimates of the effect of metallicity on cloud masses, as planets with metal-rich hosts potentially form more opaque clouds because more mass is available for condensation. Increased metallicity also pushes the point of condensation to hotter, deeper layers in the planetary atmosphere further increasing the density of the cloud. We suggest that planets around metal-rich hosts are more likely to have thick refractory clouds, and discuss the implication on the observed spectra of WASP-12b. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.03325v1-abstract-full').style.display = 'none'; document.getElementById('1610.03325v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 October, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in MNRAS, 10 pages, 1 table, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1608.08643">arXiv:1608.08643</a> <span> [<a href="https://arxiv.org/pdf/1608.08643">pdf</a>, <a href="https://arxiv.org/format/1608.08643">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/0004-637X/829/2/66">10.3847/0004-637X/829/2/66 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> On the Composition of Young, Directly Imaged Giant Planets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Moses%2C+J+I">J. I. Moses</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">M. S. Marley</a>, <a href="/search/?searchtype=author&query=Zahnle%2C+K">K. Zahnle</a>, <a href="/search/?searchtype=author&query=Line%2C+M+R">M. R. Line</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">J. J. Fortney</a>, <a href="/search/?searchtype=author&query=Barman%2C+T+S">T. S. Barman</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">C. Visscher</a>, <a href="/search/?searchtype=author&query=Lewis%2C+N+K">N. K. Lewis</a>, <a href="/search/?searchtype=author&query=Wolff%2C+M+J">M. J. Wolff</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1608.08643v1-abstract-short" style="display: inline;"> The past decade has seen significant progress on the direct detection and characterization of young, self-luminous giant planets at wide orbital separations from their host stars. Some of these planets show evidence for disequilibrium processes like transport-induced quenching in their atmospheres; photochemistry may also be important, despite the large orbital distances. These disequilibrium chem… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.08643v1-abstract-full').style.display = 'inline'; document.getElementById('1608.08643v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1608.08643v1-abstract-full" style="display: none;"> The past decade has seen significant progress on the direct detection and characterization of young, self-luminous giant planets at wide orbital separations from their host stars. Some of these planets show evidence for disequilibrium processes like transport-induced quenching in their atmospheres; photochemistry may also be important, despite the large orbital distances. These disequilibrium chemical processes can alter the expected composition, spectral behavior, thermal structure, and cooling history of the planets, and can potentially confuse determinations of bulk elemental ratios, which provide important insights into planet-formation mechanisms. Using a thermo/photochemical kinetics and transport model, we investigate the extent to which disequilibrium chemistry affects the composition and spectra of directly imaged giant exoplanets. Results for specific "young Jupiters" such as HR 8799 b and 51 Eri b are presented, as are general trends as a function of planetary effective temperature, surface gravity, incident ultraviolet flux, and strength of deep atmospheric convection. We find that quenching is very important on young Jupiters, leading to CO/CH4 and N2/NH3 ratios much greater than, and H2O mixing ratios a factor of a few less than, chemical-equilibrium predictions. Photochemistry can also be important on such planets, with CO2 and HCN being key photochemical products. Carbon dioxide becomes a major constituent when stratospheric temperatures are low and recycling of water via the H2 + OH reaction becomes kinetically stifled. Young Jupiters with effective temperatures <~ 700 K are in a particularly interesting photochemical regime that differs from both transiting hot Jupiters and our own solar-system giant planets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.08643v1-abstract-full').style.display = 'none'; document.getElementById('1608.08643v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 August, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted in The Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1604.07424">arXiv:1604.07424</a> <span> [<a href="https://arxiv.org/pdf/1604.07424">pdf</a>, <a href="https://arxiv.org/ps/1604.07424">ps</a>, <a href="https://arxiv.org/format/1604.07424">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8205/824/2/L25">10.3847/2041-8205/824/2/L25 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Hunt for Planet Nine: Atmosphere, Spectra, Evolution, and Detectability </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Laughlin%2C+G">Gregory Laughlin</a>, <a href="/search/?searchtype=author&query=Nettelmann%2C+N">Nadine Nettelmann</a>, <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R+E">Roxana E. Lupu</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Jeremic%2C+P">Pavle Jeremic</a>, <a href="/search/?searchtype=author&query=Khadder%2C+W+G">Wade G. Khadder</a>, <a href="/search/?searchtype=author&query=Hargrave%2C+M">Mason Hargrave</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1604.07424v2-abstract-short" style="display: inline;"> We investigate the physical characteristics of the Solar System's proposed Planet Nine using modeling tools with a heritage in studying Uranus and Neptune. For a range of plausible masses and interior structures, we find upper limits on the intrinsic Teff, from ~35-50 K for masses of 5-20 M_Earth, and we also explore lower Teff values. Possible planetary radii could readily span from 3 to 6 R_Eart… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1604.07424v2-abstract-full').style.display = 'inline'; document.getElementById('1604.07424v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1604.07424v2-abstract-full" style="display: none;"> We investigate the physical characteristics of the Solar System's proposed Planet Nine using modeling tools with a heritage in studying Uranus and Neptune. For a range of plausible masses and interior structures, we find upper limits on the intrinsic Teff, from ~35-50 K for masses of 5-20 M_Earth, and we also explore lower Teff values. Possible planetary radii could readily span from 3 to 6 R_Earth depending on the mass fraction of any H/He envelope. Given its cold temperature, the planet encounters significant methane condensation, which dramatically alters the atmosphere away from simple Neptune-like expectations. We find the atmosphere is strongly depleted in molecular absorption at visible wavelengths, suggesting a Rayleigh scattering atmosphere with a high geometric albedo approaching 0.75. We highlight two diagnostics for the atmosphere's temperature structure, the first being the value of the methane mixing ratio above the methane cloud. The second is the wavelength at which cloud scattering can be seen, which yields the cloud-top pressure. Surface reflection may be seen if the atmosphere is thin. Due to collision-induced opacity of H2 in the infrared, the planet would be extremely blue (instead of red) in the shortest wavelength WISE colors if methane is depleted, and would, in some cases, exist on the verge of detectability by WISE. For a range of models, thermal fluxes from ~3-5 microns are ~20 orders of magnitude larger than blackbody expectations. We report a search of the AllWISE Source Catalog for Planet Nine, but find no detection. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1604.07424v2-abstract-full').style.display = 'none'; document.getElementById('1604.07424v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 June, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 April, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to ApJ Letters, with minor changes from the submitted version</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1602.06733">arXiv:1602.06733</a> <span> [<a href="https://arxiv.org/pdf/1602.06733">pdf</a>, <a href="https://arxiv.org/format/1602.06733">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/0004-637X/821/1/9">10.3847/0004-637X/821/1/9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The atmospheric circulation of a nine-hot Jupiter sample: Probing circulation and chemistry over a wide phase space </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kataria%2C+T">Tiffany Kataria</a>, <a href="/search/?searchtype=author&query=Sing%2C+D+K">David K. Sing</a>, <a href="/search/?searchtype=author&query=Lewis%2C+N+K">Nikole K. Lewis</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Showman%2C+A+P">Adam P. Showman</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1602.06733v1-abstract-short" style="display: inline;"> We present results from an atmospheric circulation study of nine hot Jupiters that comprise a large transmission spectral survey using the Hubble and Spitzer Space Telescopes. These observations exhibit a range of spectral behavior over optical and infrared wavelengths which suggest diverse cloud and haze properties in their atmospheres. By utilizing the specific system parameters for each planet,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1602.06733v1-abstract-full').style.display = 'inline'; document.getElementById('1602.06733v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1602.06733v1-abstract-full" style="display: none;"> We present results from an atmospheric circulation study of nine hot Jupiters that comprise a large transmission spectral survey using the Hubble and Spitzer Space Telescopes. These observations exhibit a range of spectral behavior over optical and infrared wavelengths which suggest diverse cloud and haze properties in their atmospheres. By utilizing the specific system parameters for each planet, we naturally probe a wide phase space in planet radius, gravity, orbital period, and equilibrium temperature. First, we show that our model "grid" recovers trends shown in traditional parametric studies of hot Jupiters, particularly equatorial superrotation and increased day-night temperature contrast with increasing equilibrium temperature. We show how spatial temperature variations, particularly between the dayside and nightside and west and east terminators, can vary by hundreds of K, which could imply large variations in Na, K, CO and CH4 abundances in those regions. These chemical variations can be large enough to be observed in transmission with high-resolution spectrographs, such as ESPRESSO on VLT, METIS on the E-ELT, or with MIRI and NIRSpec aboard JWST. We also compare theoretical emission spectra generated from our models to available Spitzer eclipse depths for each planet, and find that the outputs from our solar-metallicity, cloud-free models generally provide a good match to many of the datasets, even without additional model tuning. Although these models are cloud-free, we can use their results to understand the chemistry and dynamics that drive cloud formation in their atmospheres. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1602.06733v1-abstract-full').style.display = 'none'; document.getElementById('1602.06733v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 February, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 pages, 10 figures; accepted to the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1511.09183">arXiv:1511.09183</a> <span> [<a href="https://arxiv.org/pdf/1511.09183">pdf</a>, <a href="https://arxiv.org/ps/1511.09183">ps</a>, <a href="https://arxiv.org/format/1511.09183">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/0004-637X/817/2/166">10.3847/0004-637X/817/2/166 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The LEECH Exoplanet Imaging Survey: Characterization of the Coldest Directly Imaged Exoplanet, GJ 504 b, and Evidence for Super-Stellar Metallicity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Skemer%2C+A+J">Andrew J. Skemer</a>, <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Zimmerman%2C+N+T">Neil T. Zimmerman</a>, <a href="/search/?searchtype=author&query=Skrutskie%2C+M+F">Michael F. Skrutskie</a>, <a href="/search/?searchtype=author&query=Leisenring%2C+J">Jarron Leisenring</a>, <a href="/search/?searchtype=author&query=Buenzli%2C+E">Esther Buenzli</a>, <a href="/search/?searchtype=author&query=Bonnefoy%2C+M">Mickael Bonnefoy</a>, <a href="/search/?searchtype=author&query=Bailey%2C+V">Vanessa Bailey</a>, <a href="/search/?searchtype=author&query=Hinz%2C+P">Philip Hinz</a>, <a href="/search/?searchtype=author&query=Defr%C3%A9re%2C+D">Denis Defr茅re</a>, <a href="/search/?searchtype=author&query=Esposito%2C+S">Simone Esposito</a>, <a href="/search/?searchtype=author&query=Apai%2C+D">D谩niel Apai</a>, <a href="/search/?searchtype=author&query=Biller%2C+B">Beth Biller</a>, <a href="/search/?searchtype=author&query=Brandner%2C+W">Wolfgang Brandner</a>, <a href="/search/?searchtype=author&query=Close%2C+L">Laird Close</a>, <a href="/search/?searchtype=author&query=Crepp%2C+J+R">Justin R. Crepp</a>, <a href="/search/?searchtype=author&query=De+Rosa%2C+R+J">Robert J. De Rosa</a>, <a href="/search/?searchtype=author&query=Desidera%2C+S">Silvano Desidera</a>, <a href="/search/?searchtype=author&query=Eisner%2C+J">Josh Eisner</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J">Jonathan Fortney</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R">Richard Freedman</a>, <a href="/search/?searchtype=author&query=Henning%2C+T">Thomas Henning</a>, <a href="/search/?searchtype=author&query=Hofmann%2C+K">Karl-Heinz Hofmann</a>, <a href="/search/?searchtype=author&query=Kopytova%2C+T">Taisiya Kopytova</a>, <a href="/search/?searchtype=author&query=Lupu%2C+R">Roxana Lupu</a> , et al. (17 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1511.09183v1-abstract-short" style="display: inline;"> As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly-imaged exoplanets were all L-type. Recently, Kuzuhara et al. (2… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.09183v1-abstract-full').style.display = 'inline'; document.getElementById('1511.09183v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1511.09183v1-abstract-full" style="display: none;"> As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly-imaged exoplanets were all L-type. Recently, Kuzuhara et al. (2013) announced the discovery of GJ 504 b, the first T dwarf exoplanet. GJ 504 b provides a unique opportunity to study the atmosphere of a new type of exoplanet with a ~500 K temperature that bridges the gap between the first directly imaged planets (~1000 K) and our own Solar System's Jupiter (~130 K). We observed GJ 504 b in three narrow L-band filters (3.71, 3.88, and 4.00 microns), spanning the red end of the broad methane fundamental absorption feature (3.3 microns) as part of the LEECH exoplanet imaging survey. By comparing our new photometry and literature photometry to a grid of custom model atmospheres, we were able to fit GJ 504 b's unusual spectral energy distribution for the first time. We find that GJ 504 b is well-fit by models with the following parameters: T_eff=544+/-10 K, g<600 m/s^2, [M/H]=0.60+/-0.12, cloud opacity parameter of f_sed=2-5, R=0.96+/-0.07 R_Jup, and log(L)=-6.13+/-0.03 L_Sun, implying a hot start mass of 3-30 M_jup for a conservative age range of 0.1-6.5 Gyr. Of particular interest, our model fits suggest that GJ 504 b has a super-stellar metallicity. Since planet formation can create objects with non-stellar metallicities, while binary star formation cannot, this result suggests that GJ 504 b formed like a planet, not like a binary companion. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.09183v1-abstract-full').style.display = 'none'; document.getElementById('1511.09183v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 November, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">resubmitted to ApJ with referee's comments</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1306.5178">arXiv:1306.5178</a> <span> [<a href="https://arxiv.org/pdf/1306.5178">pdf</a>, <a href="https://arxiv.org/ps/1306.5178">ps</a>, <a href="https://arxiv.org/format/1306.5178">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/777/1/34">10.1088/0004-637X/777/1/34 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Compositional diversity in the atmospheres of hot Neptunes, with application to GJ 436b </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Moses%2C+J+I">Julianne I. Moses</a>, <a href="/search/?searchtype=author&query=Line%2C+M+R">Michael R. Line</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Richardson%2C+M+R">Molly R. Richardson</a>, <a href="/search/?searchtype=author&query=Nettelmann%2C+N">Nadine Nettelmann</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Stevenson%2C+K+B">Kevin B. Stevenson</a>, <a href="/search/?searchtype=author&query=Madhusudhan%2C+N">Nikku Madhusudhan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1306.5178v1-abstract-short" style="display: inline;"> Neptune-sized extrasolar planets that orbit relatively close to their host stars -- often called "hot Neptunes" -- are common within the known population of exoplanets and planetary candidates. Similar to our own Uranus and Neptune, inefficient accretion of nebular gas is expected produce hot Neptunes whose masses are dominated by elements heavier than hydrogen and helium. At high atmospheric meta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1306.5178v1-abstract-full').style.display = 'inline'; document.getElementById('1306.5178v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1306.5178v1-abstract-full" style="display: none;"> Neptune-sized extrasolar planets that orbit relatively close to their host stars -- often called "hot Neptunes" -- are common within the known population of exoplanets and planetary candidates. Similar to our own Uranus and Neptune, inefficient accretion of nebular gas is expected produce hot Neptunes whose masses are dominated by elements heavier than hydrogen and helium. At high atmospheric metallicities of 10-10,000x solar, hot Neptunes will exhibit an interesting continuum of atmospheric compositions, ranging from more Neptune-like, H2-dominated atmospheres to more Venus-like, CO2-dominated atmospheres. We explore the predicted equilibrium and disequilibrium chemistry of generic hot Neptunes and find that the atmospheric composition varies strongly as a function of temperature and bulk atmospheric properties such as metallicity and the C/O ratio. Relatively exotic H2O, CO, CO2, and even O2-dominated atmospheres are possible for hot Neptunes. We apply our models to the case of GJ 436b, where we find that a CO-rich, CH4-poor atmosphere can be a natural consequence of a very high atmospheric metallicity. From comparisons of our results with Spitzer eclipse data for GJ 436b, we conclude that although the spectral fit from the high-metallicity forward models is not quite as good as the fit obtained from pure retrieval methods, the atmospheric composition predicted by these forward models is more physically and chemically plausible. High-metallicity atmospheres (orders of magnitude in excess of solar) should therefore be considered as a possibility for GJ 436b and other hot Neptunes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1306.5178v1-abstract-full').style.display = 'none'; document.getElementById('1306.5178v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 June, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">submitted to Astrophys. J. on 21 June 2013</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys. J., 777, 34 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1305.4124">arXiv:1305.4124</a> <span> [<a href="https://arxiv.org/pdf/1305.4124">pdf</a>, <a href="https://arxiv.org/ps/1305.4124">ps</a>, <a href="https://arxiv.org/format/1305.4124">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/775/1/33">10.1088/0004-637X/775/1/33 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantitatively Assessing the Role of Clouds in the Transmission Spectrum of GJ 1214b </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Kempton%2C+E+M+-">Eliza M. -R. Kempton</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Zahnle%2C+K">Kevin Zahnle</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1305.4124v2-abstract-short" style="display: inline;"> Recent observations of the super-Earth GJ 1214b show that it has a relatively featureless transmission spectrum. One suggestion is that these observations indicate that the planet's atmosphere is vertically compact, perhaps due to a water-rich composition that yields a large mean molecular weight. Another suggestion is that the atmosphere is hydrogen/helium-rich with clouds that obscure predicted… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1305.4124v2-abstract-full').style.display = 'inline'; document.getElementById('1305.4124v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1305.4124v2-abstract-full" style="display: none;"> Recent observations of the super-Earth GJ 1214b show that it has a relatively featureless transmission spectrum. One suggestion is that these observations indicate that the planet's atmosphere is vertically compact, perhaps due to a water-rich composition that yields a large mean molecular weight. Another suggestion is that the atmosphere is hydrogen/helium-rich with clouds that obscure predicted absorption features. Previous models that incorporate clouds have included their effect without a strong physical motivation for their existence. Here, we present model atmospheres of GJ 1214b that include physically-motivated clouds of two types. We model the clouds that form as a result of condensation in chemical equilibrium, as they likely do on brown dwarfs, which include KCl and ZnS for this planet. We also include clouds that form as a result of photochemistry, forming a hydrocarbon haze layer. We use a photochemical kinetics model to understand the vertical distribution and available mass of haze-forming molecules. We model both solar and enhanced-metallicity cloudy models and determine the cloud properties necessary to match observations. In enhanced-metallicity atmospheres, we find that the equilibrium clouds can match the observations of GJ 1214b if they are lofted high into the atmosphere and have a low sedimentation efficiency (fsed=0.1). We find that models with a variety of hydrocarbon haze properties can match the observations. Particle sizes from 0.01 to 0.25 micron can match the transmission spectrum with haze-forming efficiencies as low as 1-5%. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1305.4124v2-abstract-full').style.display = 'none'; document.getElementById('1305.4124v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 June, 2013; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 May, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Revised for ApJ, Figure 8 fixed in v2</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1303.3905">arXiv:1303.3905</a> <span> [<a href="https://arxiv.org/pdf/1303.3905">pdf</a>, <a href="https://arxiv.org/ps/1303.3905">ps</a>, <a href="https://arxiv.org/format/1303.3905">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/2041-8205/767/1/L12">10.1088/2041-8205/767/1/L12 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Chemistry of Impact-Generated Silicate Melt-Vapor Debris Disks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Fegley%2C%2C+B">Bruce Fegley, Jr</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1303.3905v1-abstract-short" style="display: inline;"> In the giant impact theory for lunar origin, the Moon forms from material ejected by the impact into an Earth-orbiting disk. Here we report the initial results from a silicate melt-vapor equilibrium chemistry model for such impact-generated planetary debris disks. In order to simulate the chemical behavior of a two-phase (melt+vapor) disk, we calculate the temperature-dependent pressure and chemic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1303.3905v1-abstract-full').style.display = 'inline'; document.getElementById('1303.3905v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1303.3905v1-abstract-full" style="display: none;"> In the giant impact theory for lunar origin, the Moon forms from material ejected by the impact into an Earth-orbiting disk. Here we report the initial results from a silicate melt-vapor equilibrium chemistry model for such impact-generated planetary debris disks. In order to simulate the chemical behavior of a two-phase (melt+vapor) disk, we calculate the temperature-dependent pressure and chemical composition of vapor in equilibrium with molten silicate from 2000 to 4000 K. We consider the elements O, Na, K, Fe, Si, Mg, Ca, Al, Ti, and Zn for a range of bulk silicate compositions (Earth, Moon, Mars, eucrite parent body, angrites, and ureilites). In general, the disk atmosphere is dominated by Na, Zn, and O2 at lower temperatures (< 3000 K) and SiO, O2, and O at higher temperatures. The high-temperature chemistry is consistent for any silicate melt composition, and we thus expect abundant SiO, O2, and O to be a common feature of hot, impact-generated debris disks. In addition, the saturated silicate vapor is highly oxidizing, with oxygen fugacity (fO2) values (and hence H2O/H2 and CO2/CO ratios) several orders of magnitude higher than those in a solar-composition gas. High fO2 values in the disk atmosphere are found for any silicate composition because oxygen is the most abundant element in rock. We thus expect high oxygen fugacity to be a ubiquitous feature of any silicate melt-vapor disk produced via collisions between rocky planets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1303.3905v1-abstract-full').style.display = 'none'; document.getElementById('1303.3905v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 March, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 4 figures, 2 tables, accepted for publication in ApJ Letters</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1212.1210">arXiv:1212.1210</a> <span> [<a href="https://arxiv.org/pdf/1212.1210">pdf</a>, <a href="https://arxiv.org/ps/1212.1210">ps</a>, <a href="https://arxiv.org/format/1212.1210">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/763/2/130">10.1088/0004-637X/763/2/130 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Comparison of Near-Infrared Photometry and Spectra for Y Dwarfs with a New Generation of Cool Cloudy Models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Leggett%2C+S+K">S. K. Leggett</a>, <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">M. S. Marley</a>, <a href="/search/?searchtype=author&query=Saumon%2C+D">D. Saumon</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1212.1210v2-abstract-short" style="display: inline;"> We present YJHK photometry, or a subset, for the six Y dwarfs discovered in WISE data by Cushing et al.. The data were obtained using NIRI on the Gemini North telescope. We also present a far-red spectrum obtained using GMOS-North for WISEPC J205628.90+145953.3. We compare the data to Morley et al. (2012) models, which include cloud decks of sulfide and chloride condensates. We find that the model… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1212.1210v2-abstract-full').style.display = 'inline'; document.getElementById('1212.1210v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1212.1210v2-abstract-full" style="display: none;"> We present YJHK photometry, or a subset, for the six Y dwarfs discovered in WISE data by Cushing et al.. The data were obtained using NIRI on the Gemini North telescope. We also present a far-red spectrum obtained using GMOS-North for WISEPC J205628.90+145953.3. We compare the data to Morley et al. (2012) models, which include cloud decks of sulfide and chloride condensates. We find that the models with these previously neglected clouds can reproduce the energy distributions of T9 to Y0 dwarfs quite well, other than near 5um where the models are too bright. This is thought to be because the models do not include departures from chemical equilibrium caused by vertical mixing, which would enhance the abundance of CO, decreasing the flux at 5um. Vertical mixing also decreases the abundance of NH_3, which would otherwise have strong absorption features at 1.03um and 1.52um that are not seen in the Y0 WISEPC J205628.90+145953.3. We find that the five Y0 to Y0.5 dwarfs have 300 < T_eff K < 450, 4.0 < log g < 4.5 and f_sed ~ 3. These temperatures and gravities imply a mass range of 5 - 15 M_Jupiter and ages around 5 Gyr. We suggest that WISEP J182831.08+265037.8 is a binary system, as this better explains its luminosity and color. We find that the data can be made consistent with observed trends, and generally consistent with the models, if the system is composed of a T_eff = 325 K and log g <~ 4.5 primary, and a T_eff = 300 K and log g >~ 4.0 secondary, corresponding to masses of 10 and 7 M_Jupiter and an age around 2 Gyr. If our deconvolution is correct, then the T_eff = 300 K cloud-free model fluxes at K and W2 are too faint by 0.5 - 1.0 magnitudes. We will address this discrepancy in our next generation of models, which will incorporate water clouds and mixing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1212.1210v2-abstract-full').style.display = 'none'; document.getElementById('1212.1210v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 December, 2012; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 December, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">39 pages, 10 Figures, 8 Tables. Accepted by ApJ. This revision replaces Figures 9 and 10 with B & W versions, corrects figure captions for color online only, corrects references. Text is unchanged. Tables 3, 4 and 8 are available at http://www.gemini.edu/staff/sleggett, other model data are available at http://www.ucolick.org/~cmorley/cmorley/Data.html</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1211.2996">arXiv:1211.2996</a> <span> [<a href="https://arxiv.org/pdf/1211.2996">pdf</a>, <a href="https://arxiv.org/ps/1211.2996">ps</a>, <a href="https://arxiv.org/format/1211.2996">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/763/1/25">10.1088/0004-637X/763/1/25 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Chemical consequences of the C/O ratio on hot Jupiters: Examples from WASP-12b,CoRoT-2b, XO-1b, and HD 189733b </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Moses%2C+J+I">J. I. Moses</a>, <a href="/search/?searchtype=author&query=Madhusudhan%2C+N">N. Madhusudhan</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">C. Visscher</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R+S">R. S. Freedman</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1211.2996v1-abstract-short" style="display: inline;"> Motivated by recent spectroscopic evidence for carbon-rich atmospheres on some transiting exoplanets, we investigate the influence of the C/O ratio on the chemistry, composition, and spectra of extrasolar giant planets both from a thermochemical-equilibrium perspective and from consideration of disequilibrium processes like photochemistry and transport-induced quenching. We find that although CO i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1211.2996v1-abstract-full').style.display = 'inline'; document.getElementById('1211.2996v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1211.2996v1-abstract-full" style="display: none;"> Motivated by recent spectroscopic evidence for carbon-rich atmospheres on some transiting exoplanets, we investigate the influence of the C/O ratio on the chemistry, composition, and spectra of extrasolar giant planets both from a thermochemical-equilibrium perspective and from consideration of disequilibrium processes like photochemistry and transport-induced quenching. We find that although CO is predicted to be a major atmospheric constituent on hot Jupiters for all C/O ratios, other oxygen-bearing molecules like H2O and CO2 are much more abundant when C/O < 1, whereas CH4, HCN, and C2H2 gain significantly in abundance when C/O > 1. Disequilibrium processes tend to enhance the abundance of CH4, NH3, HCN, and C2H2 over a wide range of C/O ratios. We compare the results of our models with secondary-eclipse photometric data from the Spitzer Space Telescope and conclude that (1) disequilibrium models with C/O ~ 1 are consistent with spectra of WASP-12b, XO-1b, and CoRoT-2b, confirming the possible carbon-rich nature of these planets, (2) spectra from HD 189733b are consistent with C/O ~< 1, but as the assumed metallicity is increased above solar, the required C/O ratio must increase toward 1 to prevent too much H2O absorption, (3) species like HCN can have a significant influence on spectral behavior in the 3.6 and 8.0 um Spitzer channels, potentially providing even more opacity than CH4 when C/O > 1, and (4) the very high CO2 abundance inferred for HD 189733b from near-infrared observations cannot be explained through equilibrium or disequilibrium chemistry in a H2-dominated atmosphere. We discuss possible formation mechanisms for carbon-rich hot Jupiters. The C/O ratio and bulk atmospheric metallicity provide important clues regarding the formation and evolution of the giant planets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1211.2996v1-abstract-full').style.display = 'none'; document.getElementById('1211.2996v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 November, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted in the Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys. J., 763, 25 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1207.4245">arXiv:1207.4245</a> <span> [<a href="https://arxiv.org/pdf/1207.4245">pdf</a>, <a href="https://arxiv.org/ps/1207.4245">ps</a>, <a href="https://arxiv.org/format/1207.4245">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/755/1/9">10.1088/0004-637X/755/1/9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Two nearby sub-Earth-sized exoplanet candidates in the GJ 436 system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Stevenson%2C+K+B">Kevin B. Stevenson</a>, <a href="/search/?searchtype=author&query=Harrington%2C+J">Joseph Harrington</a>, <a href="/search/?searchtype=author&query=Lust%2C+N+B">Nate B. Lust</a>, <a href="/search/?searchtype=author&query=Lewis%2C+N+K">Nikole K. Lewis</a>, <a href="/search/?searchtype=author&query=Montagnier%2C+G">Guillaume Montagnier</a>, <a href="/search/?searchtype=author&query=Moses%2C+J+I">Julianne I. Moses</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Blecic%2C+J">Jasmina Blecic</a>, <a href="/search/?searchtype=author&query=Hardy%2C+R+A">Ryan A. Hardy</a>, <a href="/search/?searchtype=author&query=Cubillos%2C+P">Patricio Cubillos</a>, <a href="/search/?searchtype=author&query=Campo%2C+C+J">Christopher J. Campo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1207.4245v1-abstract-short" style="display: inline;"> We report the detection of UCF-1.01, a strong exoplanet candidate with a radius 0.66 +/- 0.04 times that of Earth (R_{\oplus}). This sub-Earth-sized planet transits the nearby M-dwarf star GJ 436 with a period of 1.365862 +/- 8x10^{-6} days. We also report evidence of a 0.65 +/- 0.06 R_{\oplus} exoplanet candidate (labeled UCF-1.02) orbiting the same star with an undetermined period. Using the Spi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1207.4245v1-abstract-full').style.display = 'inline'; document.getElementById('1207.4245v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1207.4245v1-abstract-full" style="display: none;"> We report the detection of UCF-1.01, a strong exoplanet candidate with a radius 0.66 +/- 0.04 times that of Earth (R_{\oplus}). This sub-Earth-sized planet transits the nearby M-dwarf star GJ 436 with a period of 1.365862 +/- 8x10^{-6} days. We also report evidence of a 0.65 +/- 0.06 R_{\oplus} exoplanet candidate (labeled UCF-1.02) orbiting the same star with an undetermined period. Using the Spitzer Space Telescope, we measure the dimming of light as the planets pass in front of their parent star to assess their sizes and orbital parameters. If confirmed, UCF-1.01 and UCF-1.02 would be called GJ 436c and GJ 436d, respectively, and would be part of the first multiple-transiting-planet system outside of the Kepler field. Assuming Earth-like densities of 5.515 g/cm^3, we predict both candidates to have similar masses (~0.28 Earth-masses, M_{\oplus}, 2.6 Mars-masses) and surface gravities of ~0.65 g (where g is the gravity on Earth). UCF-1.01's equilibrium temperature (T_{eq}, where emitted and absorbed radiation balance for an equivalent blackbody) is 860 K, making the planet unlikely to harbor life as on Earth. Its weak gravitational field and close proximity to its host star imply that UCF-1.01 is unlikely to have retained its original atmosphere; however, a transient atmosphere is possible if recent impacts or tidal heating were to supply volatiles to the surface. We also present additional observations of GJ 436b during secondary eclipse. The 3.6-micron light curve shows indications of stellar activity, making a reliable secondary eclipse measurement impossible. A second non-detection at 4.5 microns supports our previous work in which we find a methane-deficient and carbon monoxide-rich dayside atmosphere. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1207.4245v1-abstract-full').style.display = 'none'; document.getElementById('1207.4245v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 July, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication with ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1207.0722">arXiv:1207.0722</a> <span> [<a href="https://arxiv.org/pdf/1207.0722">pdf</a>, <a href="https://arxiv.org/ps/1207.0722">ps</a>, <a href="https://arxiv.org/format/1207.0722">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/757/1/5">10.1088/0004-637X/757/1/5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Chemical Timescales in the Atmospheres of Highly Eccentric Exoplanets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1207.0722v2-abstract-short" style="display: inline;"> Close-in exoplanets with highly eccentric orbits are subject to large variations in incoming stellar flux between periapse and apoapse. These variations may lead to large swings in atmospheric temperature, which in turn may cause changes in the chemistry of the atmosphere from higher CO abundances at periapse to higher CH4 abundances at apoapse. Here we examine chemical timescales for CO<->CH4 int… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1207.0722v2-abstract-full').style.display = 'inline'; document.getElementById('1207.0722v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1207.0722v2-abstract-full" style="display: none;"> Close-in exoplanets with highly eccentric orbits are subject to large variations in incoming stellar flux between periapse and apoapse. These variations may lead to large swings in atmospheric temperature, which in turn may cause changes in the chemistry of the atmosphere from higher CO abundances at periapse to higher CH4 abundances at apoapse. Here we examine chemical timescales for CO<->CH4 interconversion compared to orbital timescales and vertical mixing timescales for the highly eccentric exoplanets HAT-P-2b and CoRoT-10b. As exoplanet atmospheres cool, the chemical timescales for CO<->CH4 tend to exceed orbital and/or vertical mixing timescales, leading to quenching. The relative roles of orbit-induced thermal quenching and vertical quenching depend upon mixing timescales relative to orbital timescales. For both HAT-P-2b and CoRoT-10b, vertical quenching will determine disequilibrium CO<->CH4 chemistry at faster vertical mixing rates (Kzz > 10^7 cm^2 s^-1), whereas orbit-induced thermal quenching may play a significant role at slower mixing rates (Kzz < 10^7 cm^2 s^-1). The general abundance and chemical timescale results - calculated as a function of pressure, temperature, and metallicity - can be applied for different atmospheric profiles in order to estimate the quench level and disequilibrium abundances of CO and CH4 on hydrogen-dominated exoplanets. Observations of CO and CH4 on highly eccentric exoplanets may yield important clues to the chemical and dynamical properties of their atmospheres. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1207.0722v2-abstract-full').style.display = 'none'; document.getElementById('1207.0722v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 July, 2012; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 July, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 4 figures, accepted for publication in the Astrophysical Journal; v2 corrects typos and figure resolution issues</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1206.4313">arXiv:1206.4313</a> <span> [<a href="https://arxiv.org/pdf/1206.4313">pdf</a>, <a href="https://arxiv.org/ps/1206.4313">ps</a>, <a href="https://arxiv.org/format/1206.4313">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/756/2/172">10.1088/0004-637X/756/2/172 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Neglected Clouds in T and Y Dwarf Atmospheres </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Morley%2C+C+V">Caroline V. Morley</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Saumon%2C+D">Didier Saumon</a>, <a href="/search/?searchtype=author&query=Leggett%2C+S+K">S. K. Leggett</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1206.4313v2-abstract-short" style="display: inline;"> As brown dwarfs cool, a variety of species condense in their atmospheres, forming clouds. Iron and silicate clouds shape the emergent spectra of L dwarfs, but these clouds dissipate at the L/T transition. A variety of other condensates are expected to form in cooler T dwarf atmospheres. These include Cr, MnS, Na2S, ZnS, and KCl, but the opacity of these optically thinner clouds has not been includ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1206.4313v2-abstract-full').style.display = 'inline'; document.getElementById('1206.4313v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1206.4313v2-abstract-full" style="display: none;"> As brown dwarfs cool, a variety of species condense in their atmospheres, forming clouds. Iron and silicate clouds shape the emergent spectra of L dwarfs, but these clouds dissipate at the L/T transition. A variety of other condensates are expected to form in cooler T dwarf atmospheres. These include Cr, MnS, Na2S, ZnS, and KCl, but the opacity of these optically thinner clouds has not been included in previous atmosphere models. Here, we examine their effect on model T and Y dwarf atmospheres. The cloud structures and opacities are calculated using the Ackerman & Marley (2001) cloud model, which is coupled to an atmosphere model to produce atmospheric pressure-temperature profiles in radiative-convective equilibrium. We generate a suite of models between Teff = 400 and 1300 K, log g=4.0 and 5.5, and condensate sedimentation efficiencies from fsed=2 to 5. Model spectra are compared to two red T dwarfs, Ross 458C and UGPS 0722-05; models that include clouds are found to match observed spectra significantly better than cloudless models. The emergence of sulfide clouds in cool atmospheres, particularly Na2S, may be a more natural explanation for the "cloudy" spectra of these objects, rather than the re-emergence of silicate clouds that wane at the L-to-T transition. We find that sulfide clouds provide a mechanism to match the near- and mid-infrared colors of observed T dwarfs. Our results indicate that including the opacity of condensates in T dwarf atmospheres is necessary to accurately determine the physical characteristics of many of the observed objects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1206.4313v2-abstract-full').style.display = 'none'; document.getElementById('1206.4313v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 August, 2012; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 June, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 12 figures, Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1106.3525">arXiv:1106.3525</a> <span> [<a href="https://arxiv.org/pdf/1106.3525">pdf</a>, <a href="https://arxiv.org/ps/1106.3525">ps</a>, <a href="https://arxiv.org/format/1106.3525">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/738/1/72">10.1088/0004-637X/738/1/72 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quenching of Carbon Monoxide and Methane in the Atmospheres of Cool Brown Dwarfs and Hot Jupiters </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Moses%2C+J+I">Julianne I. Moses</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1106.3525v1-abstract-short" style="display: inline;"> We explore CO-CH4 quench kinetics in the atmospheres of substellar objects using updated time-scale arguments, as suggested by a thermochemical kinetics and diffusion model that transitions from the thermochemical-equilibrium regime in the deep atmosphere to a quench-chemical regime at higher altitudes. More specifically, we examine CO quench chemistry on the T dwarf Gliese 229B and CH4 quench che… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1106.3525v1-abstract-full').style.display = 'inline'; document.getElementById('1106.3525v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1106.3525v1-abstract-full" style="display: none;"> We explore CO-CH4 quench kinetics in the atmospheres of substellar objects using updated time-scale arguments, as suggested by a thermochemical kinetics and diffusion model that transitions from the thermochemical-equilibrium regime in the deep atmosphere to a quench-chemical regime at higher altitudes. More specifically, we examine CO quench chemistry on the T dwarf Gliese 229B and CH4 quench chemistry on the hot-Jupiter HD 189733b. We describe a method for correctly calculating reverse rate coefficients for chemical reactions, discuss the predominant pathways for CO-CH4 interconversion as indicated by the model, and demonstrate that a simple time-scale approach can be used to accurately describe the behavior of quenched species when updated reaction kinetics and mixing-length-scale assumptions are used. Proper treatment of quench kinetics has important implications for estimates of molecular abundances and/or vertical mixing rates in the atmospheres of substellar objects. Our model results indicate significantly higher Kzz values than previously estimated near the CO quench level on Gliese 229B, whereas current model-data comparisons using CH4 permit a wide range of Kzz values on HD 189733b. We also use updated reaction kinetics to revise previous estimates of the Jovian water abundance, based upon the observed abundance and chemical behavior of carbon monoxide. The CO chemical/observational constraint, along with Galileo entry probe data, suggests a water abundance of approximately 0.51-2.6x solar (for a solar value of H2O/H2=9.61E-04) in Jupiter's troposphere, assuming vertical mixing from the deep atmosphere is the only source of tropospheric CO. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1106.3525v1-abstract-full').style.display = 'none'; document.getElementById('1106.3525v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 June, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2011. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">30 pages, 3 figures, accepted for publication in the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1102.0063">arXiv:1102.0063</a> <span> [<a href="https://arxiv.org/pdf/1102.0063">pdf</a>, <a href="https://arxiv.org/ps/1102.0063">ps</a>, <a href="https://arxiv.org/format/1102.0063">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/737/1/15">10.1088/0004-637X/737/1/15 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Disequilibrium Carbon, Oxygen, and Nitrogen Chemistry in the Atmospheres of HD 189733b and HD 209458b </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Moses%2C+J+I">Julianne I. Moses</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Fortney%2C+J+J">Jonathan J. Fortney</a>, <a href="/search/?searchtype=author&query=Showman%2C+A+P">Adam P. Showman</a>, <a href="/search/?searchtype=author&query=Lewis%2C+N+K">Nikole K. Lewis</a>, <a href="/search/?searchtype=author&query=Griffith%2C+C+A">Caitlin A. Griffith</a>, <a href="/search/?searchtype=author&query=Klippenstein%2C+S+J">Stephen J. Klippenstein</a>, <a href="/search/?searchtype=author&query=Shabram%2C+M">Megan Shabram</a>, <a href="/search/?searchtype=author&query=Friedson%2C+A+J">A. James Friedson</a>, <a href="/search/?searchtype=author&query=Marley%2C+M+S">Mark S. Marley</a>, <a href="/search/?searchtype=author&query=Freedman%2C+R+S">Richard S. Freedman</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1102.0063v2-abstract-short" style="display: inline;"> We have developed 1-D photochemical and thermochemical kinetics and diffusion models for the transiting exoplanets HD 189733b and HD 209458b to study the effects of disequilibrium chemistry on the atmospheric composition of "hot Jupiters." Here we investigate the coupled chemistry of neutral carbon, hydrogen, oxygen, and nitrogen species, and we compare the model results with existing transit and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1102.0063v2-abstract-full').style.display = 'inline'; document.getElementById('1102.0063v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1102.0063v2-abstract-full" style="display: none;"> We have developed 1-D photochemical and thermochemical kinetics and diffusion models for the transiting exoplanets HD 189733b and HD 209458b to study the effects of disequilibrium chemistry on the atmospheric composition of "hot Jupiters." Here we investigate the coupled chemistry of neutral carbon, hydrogen, oxygen, and nitrogen species, and we compare the model results with existing transit and eclipse observations. We find that the vertical profiles of molecular constituents are significantly affected by transport-induced quenching and photochemistry, particularly on cooler HD 189733b; however, the warmer stratospheric temperatures on HD 209458b can help maintain thermochemical equilibrium and reduce the effects of disequilibrium chemistry. For both planets, the methane and ammonia mole fractions are found to be enhanced over their equilibrium values at pressures of a few bar to less than a mbar due to transport-induced quenching, but CH4 and NH3 are photochemically removed at higher altitudes. Atomic species, unsaturated hydrocarbons (particularly C2H2), some nitriles (particularly HCN), and radicals like OH, CH3, and NH2 are enhanced overequilibrium predictions because of quenching and photochemistry. In contrast, CO, H2O, N2, and CO2 more closely follow their equilibrium profiles, except at pressures < 1 microbar, where CO, H2O, and N2 are photochemically destroyed and CO2 is produced before its eventual high-altitude destruction. The enhanced abundances of HCN, CH4, and NH3 in particular are expected to affect the spectral signatures and thermal profiles HD 189733b and other, relatively cool, close-in transiting exoplanets. We examine the sensitivity of our results to the assumed temperature structure and eddy diffusion coefficientss and discuss further observational consequences of these models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1102.0063v2-abstract-full').style.display = 'none'; document.getElementById('1102.0063v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 May, 2011; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 January, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2011. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">40 pages, 16 figures, accepted for publication in Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys. J., 737, 15 (2011) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1006.3508">arXiv:1006.3508</a> <span> [<a href="https://arxiv.org/pdf/1006.3508">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1039/c003954c">10.1039/c003954c <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> On the abundance of non-cometary HCN on Jupiter </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Moses%2C+J+I">Julianne I. Moses</a>, <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Keane%2C+T+C">Thomas C. Keane</a>, <a href="/search/?searchtype=author&query=Sperier%2C+A">Aubrey Sperier</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1006.3508v1-abstract-short" style="display: inline;"> Using one-dimensional thermochemical/photochemical kinetics and transport models, we examine the chemistry of nitrogen-bearing species in the Jovian troposphere in an attempt to explain the low observational upper limit for HCN. We track the dominant mechanisms for interconversion of N2-NH3 and HCN-NH3 in the deep, hightemperature troposphere and predict the rate-limiting step for the quenching of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1006.3508v1-abstract-full').style.display = 'inline'; document.getElementById('1006.3508v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1006.3508v1-abstract-full" style="display: none;"> Using one-dimensional thermochemical/photochemical kinetics and transport models, we examine the chemistry of nitrogen-bearing species in the Jovian troposphere in an attempt to explain the low observational upper limit for HCN. We track the dominant mechanisms for interconversion of N2-NH3 and HCN-NH3 in the deep, hightemperature troposphere and predict the rate-limiting step for the quenching of HCN at cooler tropospheric altitudes. Consistent with other investigations that were based solely on time-scale arguments, our models suggest that transport-induced quenching of thermochemically derived HCN leads to very small predicted mole fractions of hydrogen cyanide in Jupiter's upper troposphere. By the same token, photochemical production of HCN is ineffective in Jupiter's troposphere: CH4-NH3 coupling is inhibited by the physical separation of the CH4 photolysis region in the upper stratosphere from the NH3 photolysis and condensation region in the troposphere, and C2H2-NH3 coupling is inhibited by the low tropospheric abundance of C2H2. The upper limits from infrared and submillimeter observations can be used to place constraints on the production of HCN and other species from lightning and thundershock sources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1006.3508v1-abstract-full').style.display = 'none'; document.getElementById('1006.3508v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 June, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2010. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">56 pages, 0 tables, 6 figures. Submitted to Faraday Discussions [in press]</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Faraday Discussions, 2010, 147, 103-136 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1003.6077">arXiv:1003.6077</a> <span> [<a href="https://arxiv.org/pdf/1003.6077">pdf</a>, <a href="https://arxiv.org/ps/1003.6077">ps</a>, <a href="https://arxiv.org/format/1003.6077">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.icarus.2010.03.029">10.1016/j.icarus.2010.03.029 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Deep Water Abundance on Jupiter: New Constraints from Thermochemical Kinetics and Diffusion Modeling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Moses%2C+J+I">Julianne I. Moses</a>, <a href="/search/?searchtype=author&query=Saslow%2C+S+A">Sarah A. Saslow</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1003.6077v2-abstract-short" style="display: inline;"> We have developed a one-dimensional thermochemical kinetics and diffusion model for Jupiter's atmosphere that accurately describes the transition from the thermochemical regime in the deep troposphere (where chemical equilibrium is established) to the quenched regime in the upper troposphere (where chemical equilibrium is disrupted). The model is used to calculate chemical abundances of tropospher… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1003.6077v2-abstract-full').style.display = 'inline'; document.getElementById('1003.6077v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1003.6077v2-abstract-full" style="display: none;"> We have developed a one-dimensional thermochemical kinetics and diffusion model for Jupiter's atmosphere that accurately describes the transition from the thermochemical regime in the deep troposphere (where chemical equilibrium is established) to the quenched regime in the upper troposphere (where chemical equilibrium is disrupted). The model is used to calculate chemical abundances of tropospheric constituents and to identify important chemical pathways for CO-CH4 interconversion in hydrogen-dominated atmospheres. In particular, the observed mole fraction and chemical behavior of CO is used to indirectly constrain the Jovian water inventory. Our model can reproduce the observed tropospheric CO abundance provided that the water mole fraction lies in the range (0.25-6.0) x 10^-3 in Jupiter's deep troposphere, corresponding to an enrichment of 0.3 to 7.3 times the protosolar abundance (assumed to be H2O/H2 = 9.61 x 10^-4). Our results suggest that Jupiter's oxygen enrichment is roughly similar to that for carbon, nitrogen, and other heavy elements, and we conclude that formation scenarios that require very large (>8 times solar) enrichments in water can be ruled out. We also evaluate and refine the simple time-constant arguments currently used to predict the quenched CO abundance on Jupiter, other giant planets, and brown dwarfs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1003.6077v2-abstract-full').style.display = 'none'; document.getElementById('1003.6077v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 June, 2010; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 March, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2010. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">42 pages, 7 figures, 4 tables, with note added in proof. Accepted for publication in Icarus [in press]</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1001.3639">arXiv:1001.3639</a> <span> [<a href="https://arxiv.org/pdf/1001.3639">pdf</a>, <a href="https://arxiv.org/ps/1001.3639">ps</a>, <a href="https://arxiv.org/format/1001.3639">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0004-637X/716/2/1060">10.1088/0004-637X/716/2/1060 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars III. Iron, Magnesium, and Silicon </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Lodders%2C+K">Katharina Lodders</a>, <a href="/search/?searchtype=author&query=Fegley%2C+B">Bruce Fegley Jr</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1001.3639v1-abstract-short" style="display: inline;"> We use thermochemical equilibrium calculations to model iron, magnesium, and silicon chemistry in the atmospheres of giant planets, brown dwarfs, extrasolar giant planets (EGPs), and low-mass stars. The behavior of individual Fe-, Mg-, and Si-bearing gases and condensates is determined as a function of temperature, pressure, and metallicity. Our results are thus independent of any particular mod… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1001.3639v1-abstract-full').style.display = 'inline'; document.getElementById('1001.3639v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1001.3639v1-abstract-full" style="display: none;"> We use thermochemical equilibrium calculations to model iron, magnesium, and silicon chemistry in the atmospheres of giant planets, brown dwarfs, extrasolar giant planets (EGPs), and low-mass stars. The behavior of individual Fe-, Mg-, and Si-bearing gases and condensates is determined as a function of temperature, pressure, and metallicity. Our results are thus independent of any particular model atmosphere. The condensation of Fe metal strongly affects iron chemistry by efficiently removing Fe-bearing species from the gas phase. Monatomic Fe is the most abundant Fe-bearing gas throughout the atmospheres of EGPs and L dwarfs and in the deep atmospheres of giant planets and T dwarfs. Mg- and Si-bearing gases are effectively removed from the atmosphere by forsterite (Mg2SiO4) and enstatite (MgSiO3) cloud formation. Monatomic Mg is the dominant magnesium gas throughout the atmospheres of EGPs and L dwarfs and in the deep atmospheres of giant planets and T dwarfs. Silicon monoxide (SiO) is the most abundant Si-bearing gas in the deep atmospheres of brown dwarfs and EGPs, whereas SiH4 is dominant in the deep atmosphere of Jupiter and other gas giant planets. Several other Fe-, Mg-, and Si-bearing gases become increasingly important with decreasing effective temperature. In principle, a number of Fe, Mg, and Si gases are potential tracers of weather or diagnostic of temperature in substellar atmospheres. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1001.3639v1-abstract-full').style.display = 'none'; document.getElementById('1001.3639v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 January, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2010. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">42 pages, 15 figures, submitted to the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/astro-ph/0511136">arXiv:astro-ph/0511136</a> <span> [<a href="https://arxiv.org/pdf/astro-ph/0511136">pdf</a>, <a href="https://arxiv.org/ps/astro-ph/0511136">ps</a>, <a href="https://arxiv.org/format/astro-ph/0511136">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics">astro-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1086/506245">10.1086/506245 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars II. Sulfur and Phosphorus </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Lodders%2C+K">Katharina Lodders</a>, <a href="/search/?searchtype=author&query=Fegley%2C+B">Bruce Fegley Jr</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="astro-ph/0511136v2-abstract-short" style="display: inline;"> Thermochemical equilibrium and kinetic calculations are used to model sulfur and phosphorus chemistry in giant planets, brown dwarfs, and extrasolar giant planets (EGPs). The chemical behavior of individual S- and P-bearing gases and condensates is determined as a function of pressure, temperature, and metallicity. The results are independent of particular model atmospheres and, in principle, th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('astro-ph/0511136v2-abstract-full').style.display = 'inline'; document.getElementById('astro-ph/0511136v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="astro-ph/0511136v2-abstract-full" style="display: none;"> Thermochemical equilibrium and kinetic calculations are used to model sulfur and phosphorus chemistry in giant planets, brown dwarfs, and extrasolar giant planets (EGPs). The chemical behavior of individual S- and P-bearing gases and condensates is determined as a function of pressure, temperature, and metallicity. The results are independent of particular model atmospheres and, in principle, the equilibrium composition along the pressure-temperature profile of any object can be determined. Hydrogen sulfide (H2S) is the dominant S-bearing gas throughout substellar atmospheres and approximately represents the atmospheric sulfur inventory. Silicon sulfide (SiS) is a potential tracer of weather in substellar atmospheres. Disequilibrium abundances of phosphine (PH3) approximately representative of the total atmospheric phosphorus inventory are expected to be mixed upward into the observable atmospheres of giant planets and T dwarfs. In hotter objects, several P-bearing gases (e.g., P2, PH3, PH2, PH, HCP) become increasingly important at high temperatures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('astro-ph/0511136v2-abstract-full').style.display = 'none'; document.getElementById('astro-ph/0511136v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 June, 2006; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 November, 2005; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2005. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">38 pages, 8 figures, accepted for Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys.J.648:1181-1195,2006 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/astro-ph/0501128">arXiv:astro-ph/0501128</a> <span> [<a href="https://arxiv.org/pdf/astro-ph/0501128">pdf</a>, <a href="https://arxiv.org/ps/astro-ph/0501128">ps</a>, <a href="https://arxiv.org/format/astro-ph/0501128">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics">astro-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1086/428493">10.1086/428493 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Chemical Constraints on the Water and Total Oxygen Abundances in the Deep Atmosphere of Saturn </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Visscher%2C+C">Channon Visscher</a>, <a href="/search/?searchtype=author&query=Fegley%2C+B">Bruce Fegley Jr</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="astro-ph/0501128v1-abstract-short" style="display: inline;"> Thermochemical equilibrium and kinetic calculations for the trace gases CO, PH3, and SiH4 give three independent constraints on the water and total oxygen abundances of Saturn's deep atmosphere. A lower limit to the water abundance of H2O/H2 > 1.7 x 10^-3 is given by CO chemistry while an upper limit of H2O/H2 < 5.5 x 10^-3 is given by PH3 chemistry. A combination of the CO and PH3 constraints i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('astro-ph/0501128v1-abstract-full').style.display = 'inline'; document.getElementById('astro-ph/0501128v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="astro-ph/0501128v1-abstract-full" style="display: none;"> Thermochemical equilibrium and kinetic calculations for the trace gases CO, PH3, and SiH4 give three independent constraints on the water and total oxygen abundances of Saturn's deep atmosphere. A lower limit to the water abundance of H2O/H2 > 1.7 x 10^-3 is given by CO chemistry while an upper limit of H2O/H2 < 5.5 x 10^-3 is given by PH3 chemistry. A combination of the CO and PH3 constraints indicates a water enrichment on Saturn of 1.9 to 6.1 times the solar system abundance (H2O/H2 = 8.96 x 10^-4). The total oxygen abundance must be at least 1.7 times the solar system abundance (O/H2 = 1.16 x 10^-3) in order for the SiH4 to remain below a detection limit of SiH4/H2 < 2 x 10^-10. A combination of the CO, PH3, and SiH4 constraints suggests that the total oxygen abundance on Saturn is 3.2 to 6.4 times the solar system abundance. Our results indicate that oxygen on Saturn is less enriched than other heavy elements (such as C and P) relative to a solar system composition. This work was supported by NASA NAG5-11958. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('astro-ph/0501128v1-abstract-full').style.display = 'none'; document.getElementById('astro-ph/0501128v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 January, 2005; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2005. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 2 figures, accepted for publication in the Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophys.J. 623 (2005) 1221 </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> </main> <footer> <div class="columns is-desktop" role="navigation" aria-label="Secondary">  <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/about">About</a></li> <li><a href="https://info.arxiv.org/help">Help</a></li> </ul> </div> <div class="column"> <ul class="nav-spaced"> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>contact arXiv</title><desc>Click here to contact arXiv</desc><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 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