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</div> <div class="control"> <button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.06884">arXiv:2411.06884</a> <span> [<a href="https://arxiv.org/pdf/2411.06884">pdf</a>, <a href="https://arxiv.org/format/2411.06884">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="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> X-Shooting ULLYSES: Massive stars at low metallicity VI. Atmosphere and mass-loss properties of O-type giants in the Small Magellanic Cloud </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Backs%2C+F">Frank Backs</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=de+Koter%2C+A">A. de Koter</a>, <a href="/search/astro-ph?searchtype=author&query=Kaper%2C+L">L. Kaper</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J+S">J. S. Vink</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">J. Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Sundqvist%2C+J">J. Sundqvist</a>, <a href="/search/astro-ph?searchtype=author&query=Tramper%2C+F">F. Tramper</a>, <a href="/search/astro-ph?searchtype=author&query=Sana%2C+H">H. Sana</a>, <a href="/search/astro-ph?searchtype=author&query=Bernini-Peron%2C+M">M. Bernini-Peron</a>, <a href="/search/astro-ph?searchtype=author&query=Bestenlehner%2C+J+M">J. M. Bestenlehner</a>, <a href="/search/astro-ph?searchtype=author&query=Crowther%2C+P+A">P. A. Crowther</a>, <a href="/search/astro-ph?searchtype=author&query=Hawcroft%2C+C">C. Hawcroft</a>, <a href="/search/astro-ph?searchtype=author&query=Ignace%2C+R">R. Ignace</a>, <a href="/search/astro-ph?searchtype=author&query=Kuiper%2C+R">R. Kuiper</a>, <a href="/search/astro-ph?searchtype=author&query=van+Loon%2C+J+T">J. Th. van Loon</a>, <a href="/search/astro-ph?searchtype=author&query=Mahy%2C+L">L. Mahy</a>, <a href="/search/astro-ph?searchtype=author&query=Marcolino%2C+W">W. Marcolino</a>, <a href="/search/astro-ph?searchtype=author&query=Najarro%2C+F">F. Najarro</a>, <a href="/search/astro-ph?searchtype=author&query=Oskinova%2C+L+M">L. M. Oskinova</a>, <a href="/search/astro-ph?searchtype=author&query=Pauli%2C+D">D. Pauli</a>, <a href="/search/astro-ph?searchtype=author&query=Ramachandran%2C+V">V. Ramachandran</a>, <a href="/search/astro-ph?searchtype=author&query=Sander%2C+A+A+C">A. A. C. Sander</a>, <a href="/search/astro-ph?searchtype=author&query=Verhamme%2C+O">O. Verhamme</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="2411.06884v1-abstract-short" style="display: inline;"> Mass loss through a stellar wind is an important physical process that steers the evolution of massive stars and controls the properties of their end-of-life products, such as the supernova type and the mass of compact remnants. For an accurate mass loss determination, the inhomogeneities in the wind, known as clumping, needs to be taking into account. We aim to improve empirical estimates of mass… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06884v1-abstract-full').style.display = 'inline'; document.getElementById('2411.06884v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.06884v1-abstract-full" style="display: none;"> Mass loss through a stellar wind is an important physical process that steers the evolution of massive stars and controls the properties of their end-of-life products, such as the supernova type and the mass of compact remnants. For an accurate mass loss determination, the inhomogeneities in the wind, known as clumping, needs to be taking into account. We aim to improve empirical estimates of mass loss and wind clumping for hot main-sequence massive stars, study the dependence of both properties on the metallicity, and compare the theoretical predictions to our findings. We analyzed the optical and UV spectra of 13 O-type stars in the Small Magellanic Cloud galaxy, which has a metallicity of $\sim 0.2\,Z_\odot$. We quantified the stellar atmosphere, outflow, and wind-clumping properties. To probe the role of metallicity, we compared our findings to studies of Galactic and Large Magellanic Cloud samples that were analyzed with similar methods. We find significant variations in the wind-clumping properties of the target stars, with clumping starting at flow velocities $0.01 - 0.23$ of the terminal wind velocity and reaching clumping factors $f_{\rm cl} = 2 - 30$. In the luminosity ($\log L / L_{\odot} = 5.0 - 6.0$) and metallicity ($Z/Z_{\odot} = 0.2 - 1$) range we considered, we find that the scaling of the mass loss $\dot{M}$ with metallicity $Z$ varies with luminosity. At $\log L/L_{\odot} = 5.75$, we find $\dot{M} \propto Z^m$ with $m = 1.02 \pm 0.30$, in agreement with pioneering work in the field. For lower luminosities, however, we obtain a significantly steeper scaling of $m > 2$. The monotonically decreasing $m(L)$ behavior adds a complexity to the functional description of the mass-loss rate of hot massive stars. Although the trend is present in the predictions, it is much weaker than we found here. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06884v1-abstract-full').style.display = 'none'; document.getElementById('2411.06884v1-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 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">37 pages, 29 figures. Accepted for publication in Astronomy and Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.14937">arXiv:2410.14937</a> <span> [<a href="https://arxiv.org/pdf/2410.14937">pdf</a>, <a href="https://arxiv.org/format/2410.14937">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="Astrophysics of Galaxies">astro-ph.GA</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/10.1051/0004-6361/202451169">10.1051/0004-6361/202451169 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-Shooting ULLYSES: Massive Stars at low metallicity IX: Empirical constraints on mass-loss rates and clumping parameters for OB supergiants in the Large Magellanic Cloud </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Verhamme%2C+O">O. Verhamme</a>, <a href="/search/astro-ph?searchtype=author&query=Sundqvist%2C+J">J. Sundqvist</a>, <a href="/search/astro-ph?searchtype=author&query=de+Koter%2C+A">A. de Koter</a>, <a href="/search/astro-ph?searchtype=author&query=Sana%2C+H">H. Sana</a>, <a href="/search/astro-ph?searchtype=author&query=Backs%2C+F">F. Backs</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=Najarro%2C+F">F. Najarro</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">J. Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J+S">J. S. Vink</a>, <a href="/search/astro-ph?searchtype=author&query=Crowther%2C+P+A">P. A. Crowther</a>, <a href="/search/astro-ph?searchtype=author&query=Kub%C3%A1tov%C3%A1%2C+B">B. Kub谩tov谩</a>, <a href="/search/astro-ph?searchtype=author&query=Sander%2C+A+A+C">A. A. C. Sander</a>, <a href="/search/astro-ph?searchtype=author&query=Bernini-Peron%2C+M">M. Bernini-Peron</a>, <a href="/search/astro-ph?searchtype=author&query=Kuiper%2C+R">R. Kuiper</a>, <a href="/search/astro-ph?searchtype=author&query=Prinja%2C+R+K">R. K. Prinja</a>, <a href="/search/astro-ph?searchtype=author&query=Schillemans%2C+P">P. Schillemans</a>, <a href="/search/astro-ph?searchtype=author&query=Shenar%2C+T">T. Shenar</a>, <a href="/search/astro-ph?searchtype=author&query=van+Loon%2C+J+T">J. Th. van Loon</a>, <a href="/search/astro-ph?searchtype=author&query=collaboration%2C+X">XShootu collaboration</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="2410.14937v2-abstract-short" style="display: inline;"> Context. Current implementations of mass loss for hot, massive stars in stellar evolution models include a sharp increase in mass loss when blue supergiants become cooler than Teff 20-22kK. This drastic mass-loss jump has been motivated by the potential presence of a so-called bistability ionisation effect, which may occur for line-driven winds in this temperature region due to recombination of im… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.14937v2-abstract-full').style.display = 'inline'; document.getElementById('2410.14937v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.14937v2-abstract-full" style="display: none;"> Context. Current implementations of mass loss for hot, massive stars in stellar evolution models include a sharp increase in mass loss when blue supergiants become cooler than Teff 20-22kK. This drastic mass-loss jump has been motivated by the potential presence of a so-called bistability ionisation effect, which may occur for line-driven winds in this temperature region due to recombination of important line-driving ions. Aims. We perform quantitative spectroscopy using UV (ULLYSES program) and optical (XShootU collaboration) data for 17 OB-supergiant stars in the LMC (covering the range Teff 14-32kK), deriving absolute constraints on global stellar, wind, and clumping parameters. We examine whether there are any empirical signs of a mass-loss jump in the investigated region, and we study the clumped nature of the wind. Methods. We use a combination of the model atmosphere code fastwind and the genetic algorithm code Kiwi-GA to fit synthetic spectra of a multitude of diagnostic spectral lines in the optical and UV. Results. We find no signs of any upward mass loss jump anywhere in the examined region. Standard theoretical comparison models, which include a strong bistability jump thus severely over predict the empirical mass-loss rates on the cool side of the predicted jump. Additionally, we find that on average about 40% of the total wind mass seems to reside in the diluted medium in between dense clumps. Conclusions. Our derived mass-loss rates suggest that for applications like stellar evolution one should not include a drastic bistability jump in mass loss for stars in the temperature and luminosity region investigated here. The derived high values of interclump density further suggest that the common assumption of an effectively void interclump medium (applied in the vast majority of spectroscopic studies of hot star winds) is not generally valid in this parameter regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.14937v2-abstract-full').style.display = 'none'; document.getElementById('2410.14937v2-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> 23 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 692, A91 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.11713">arXiv:2408.11713</a> <span> [<a href="https://arxiv.org/pdf/2408.11713">pdf</a>, <a href="https://arxiv.org/format/2408.11713">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="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> Properties of intermediate- to high-mass stars in the young cluster M17 -- Characterizing the (pre-)zero-age main sequence </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Backs%2C+F">Frank Backs</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=Ram%C3%ADrez-Tannus%2C+M+C">M. C. Ram铆rez-Tannus</a>, <a href="/search/astro-ph?searchtype=author&query=Derkink%2C+A+R">A. R. Derkink</a>, <a href="/search/astro-ph?searchtype=author&query=de+Koter%2C+A">A. de Koter</a>, <a href="/search/astro-ph?searchtype=author&query=Poorta%2C+J">J. Poorta</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">J. Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Kaper%2C+L">Lex Kaper</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="2408.11713v1-abstract-short" style="display: inline;"> The outcome of the formation of massive stars is an important anchor point in their evolution. It provides insight into the physics of the assembly process, and sets the conditions for stellar evolution. We characterize a population of 18 highly reddened O4.5 to B9 stars in the very young massive star-forming region M17. Their properties allow us to identify the empirical location of the ZAMS, and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.11713v1-abstract-full').style.display = 'inline'; document.getElementById('2408.11713v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.11713v1-abstract-full" style="display: none;"> The outcome of the formation of massive stars is an important anchor point in their evolution. It provides insight into the physics of the assembly process, and sets the conditions for stellar evolution. We characterize a population of 18 highly reddened O4.5 to B9 stars in the very young massive star-forming region M17. Their properties allow us to identify the empirical location of the ZAMS, and rotation and mass-loss rate of stars there. We performed quantitative spectroscopic modeling of VLT/X-shooter spectra using NLTE atmosphere code Fastwind and fitting approach Kiwi-GA. The observed SEDs were used to determine the line-of-sight extinction. From a comparison of their positions in the HRD with MIST evolutionary tracks, we inferred the stellar masses and ages. We find an age of $0.4_{-0.2}^{+0.6}$ Myr for our sample, however we also identify a strong relation between the age and the mass of the stars. The extinction towards the sources ranges from $A_V = 3.6$ to 10.6. Stars more massive than 10 M$_{\odot}$ have reached the ZAMS. Their projected ZAMS spin rate distribution extends to 0.3 of the critical velocity; their mass-loss rates agree with those of other main-sequence OB stars. Stars with a mass in the range $3 < M/$M$_{\odot} < 7$ are still on the pre-main sequence (PMS). Evolving their $v \sin i$ to the ZAMS yields values up to $\sim 0.6 v_{\rm crit}$. For PMS stars without disks, we find tentative mass-loss rates up to $10^{-8.5}\,$M$_{\odot}$\,yr$^{-1}$. We constrain the empirical location of the ZAMS for massive ($10 < M/$M$_{\odot} < 50$) stars. The ZAMS rotation rates for intermediate-mass stars are twice as high as for massive stars, suggesting that the angular momentum gain processes differ between the two groups. The relation between the age and mass of the stars suggests a lag in the formation of more massive stars relative to lower mass stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.11713v1-abstract-full').style.display = 'none'; document.getElementById('2408.11713v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">37 pages, 31 figures, accepted for publication in A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.14216">arXiv:2407.14216</a> <span> [<a href="https://arxiv.org/pdf/2407.14216">pdf</a>, <a href="https://arxiv.org/format/2407.14216">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="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> X-Shooting ULLYSES: Massive stars at low metallicity VII. Stellar and wind properties of B supergiants in the Small Magellanic Cloud </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bernini-Peron%2C+M">M. Bernini-Peron</a>, <a href="/search/astro-ph?searchtype=author&query=Sander%2C+A+A+C">A. A. C. Sander</a>, <a href="/search/astro-ph?searchtype=author&query=Ramachandran%2C+V">V. Ramachandran</a>, <a href="/search/astro-ph?searchtype=author&query=Oskinova%2C+L+M">L. M. Oskinova</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J+S">J. S. Vink</a>, <a href="/search/astro-ph?searchtype=author&query=Verhamme%2C+O">O. Verhamme</a>, <a href="/search/astro-ph?searchtype=author&query=Najarro%2C+F">F. Najarro</a>, <a href="/search/astro-ph?searchtype=author&query=Josiek%2C+J">J. Josiek</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=Crowther%2C+P+A">P. A. Crowther</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez-Gonz%C3%A1lez%2C+V+M+A">V. M. A. G贸mez-Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Gormaz-Matamala%2C+A+C">A. C. Gormaz-Matamala</a>, <a href="/search/astro-ph?searchtype=author&query=Hawcroft%2C+C">C. Hawcroft</a>, <a href="/search/astro-ph?searchtype=author&query=Kuiper%2C+R">R. Kuiper</a>, <a href="/search/astro-ph?searchtype=author&query=Mahy%2C+L">L. Mahy</a>, <a href="/search/astro-ph?searchtype=author&query=Marcolino%2C+W+L+F">W. L. F. Marcolino</a>, <a href="/search/astro-ph?searchtype=author&query=Martins%2C+L+P">L. P. Martins</a>, <a href="/search/astro-ph?searchtype=author&query=Mehner%2C+A">A. Mehner</a>, <a href="/search/astro-ph?searchtype=author&query=Parsons%2C+T+N">T. N. Parsons</a>, <a href="/search/astro-ph?searchtype=author&query=Pauli%2C+D">D. Pauli</a>, <a href="/search/astro-ph?searchtype=author&query=Shenar%2C+T">T. Shenar</a>, <a href="/search/astro-ph?searchtype=author&query=Schootemeijer%2C+A">A. Schootemeijer</a>, <a href="/search/astro-ph?searchtype=author&query=Todt%2C+H">H. Todt</a>, <a href="/search/astro-ph?searchtype=author&query=van+Loon%2C+J+T">J. Th. van Loon</a>, <a href="/search/astro-ph?searchtype=author&query=collaboration%2C+t+X">the XShootU collaboration</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="2407.14216v1-abstract-short" style="display: inline;"> Context. B supergiants (BSGs) represent an important connection between the main sequence and more extreme evolutionary stages of massive stars. Additionally, lying toward the cool end of the hot star regime, determining their wind properties is crucial to constrain the evolution and feedback of massive stars as, for instance, they might manifest the bi-stability jump phenomenon. Aims. We undertak… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.14216v1-abstract-full').style.display = 'inline'; document.getElementById('2407.14216v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.14216v1-abstract-full" style="display: none;"> Context. B supergiants (BSGs) represent an important connection between the main sequence and more extreme evolutionary stages of massive stars. Additionally, lying toward the cool end of the hot star regime, determining their wind properties is crucial to constrain the evolution and feedback of massive stars as, for instance, they might manifest the bi-stability jump phenomenon. Aims. We undertake a detailed analysis of a representative sample of 18 Small Magellanic Cloud (SMC) BSGs within the ULLYSES and XShootU datasets. Our UV and optical analysis spans BSGs from B0 to B8 - covering the bi-stability jump region. We aim to evaluate their evolutionary status and verify what their wind properties say about the bi-stability jump in a low-metallicity environment. Methods. We used the CMFGEN to model the spectra and photometry (from UV to infrared) of our sample. We compare our results with different evolutionary models, with previous determinations in the literature of OB stars, and with diverging mass-loss recipes at the bi-stability jump. Additionally, we provide the first BSG models in the SMC including X-rays. Results. (i) Within a single-stellar evolution framework, the evolutionary status of early BSGs seem less clear than that of late BSGs, which agree with H-shell burning models. (ii) UV analysis shows evidence that BSGs contain X-rays in their atmospheres, for which we provide constraints. In general, we find higher X-ray luminosity (close to the standard log(L_X/L) ~ -7) for early BSGs. For cooler BSGs, lower values are preferred, log(L_X/L) ~ -8.5. (iii) The obtained mass-loss rates suggest neither a jump nor a monotonic decrease with temperature. Instead, a rather constant trend is observed, which is at odds with the increase found for Galactic BSGs. (iv) The wind velocity behavior with temperature shows a sharp drop at ~19 kK, similar to what is observed for Galactic BSGs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.14216v1-abstract-full').style.display = 'none'; document.getElementById('2407.14216v1-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 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">33 pages (23+10)+(22 at Zenodo), 34 figures (21+13)+(21 at Zenodo), 7 tables (3+4)+(1 at Zenodo), accepted for publication</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.06775">arXiv:2407.06775</a> <span> [<a href="https://arxiv.org/pdf/2407.06775">pdf</a>, <a href="https://arxiv.org/format/2407.06775">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="Astrophysics of Galaxies">astro-ph.GA</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/10.1051/0004-6361/202348478">10.1051/0004-6361/202348478 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Empirical mass-loss rates and clumping properties of O-type stars in the LMC </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hawcroft%2C+C">C. Hawcroft</a>, <a href="/search/astro-ph?searchtype=author&query=Mahy%2C+L">L. Mahy</a>, <a href="/search/astro-ph?searchtype=author&query=Sana%2C+H">H. Sana</a>, <a href="/search/astro-ph?searchtype=author&query=Sundqvist%2C+J+O">J. O. Sundqvist</a>, <a href="/search/astro-ph?searchtype=author&query=Abdul-Masih%2C+M">M. Abdul-Masih</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=Decin%2C+L">L. Decin</a>, <a href="/search/astro-ph?searchtype=author&query=deKoter%2C+A">A. deKoter</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">J. Puls</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="2407.06775v1-abstract-short" style="display: inline;"> We constrain wind parameters of a sample of 18 O-type stars in the LMC, through analysis with stellar atmosphere and wind models including the effects of optically thick clumping. This allows us to determine the most accurate spectroscopic mass-loss and wind structure properties of massive stars at sub-solar metallicity to date and gain insight into the impact of metallicity on massive stellar win… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06775v1-abstract-full').style.display = 'inline'; document.getElementById('2407.06775v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.06775v1-abstract-full" style="display: none;"> We constrain wind parameters of a sample of 18 O-type stars in the LMC, through analysis with stellar atmosphere and wind models including the effects of optically thick clumping. This allows us to determine the most accurate spectroscopic mass-loss and wind structure properties of massive stars at sub-solar metallicity to date and gain insight into the impact of metallicity on massive stellar winds. Combining high signal to noise (S/N) ratio spectroscopy in the UV and optical gives us access to diagnostics of multiple different physical processes in the stellar wind. We produce synthetic spectra using the stellar atmosphere modelling code FASTWIND, and reproduce the observed spectra using a genetic algorithm based fitting technique. We empirically constrain 15 physical parameters associated with the stellar and wind properties, including temperature, surface gravity, surface abundances, rotation, macroturbulence and wind parameters. We find, on average, mass-loss rates a factor of 4-5 lower than those predicted by Vink et al. 2001, in good agreement with predictions from Bjorklund et al. 2021, and the best agreement with those from Krticka et al. 2018. In the 'weak-wind' regime we find mass-loss rates orders of magnitude below any theoretical predictions. We find a positive correlation of clumping factors (fcl) with effective temperature with an average fcl = 14 +- 8 for the full sample. Above 38 kK an average 46 +- 24% of the wind velocity span is covered by clumps and the interclump density is 10-30% of the mean wind. Below an effective temperature of roughly 38 kK there must be additional light leakage for supergiants. For dwarf stars at low temperatures there is a statistical preference for very low clump velocity spans, however it is unclear if this can be physically motivated as there are no clearly observable wind signatures in UV diagnostics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06775v1-abstract-full').style.display = 'none'; document.getElementById('2407.06775v1-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> 9 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">12 pages with 6 figures, plus 16 pages and 18 figures in appendix. Accepted for publication 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 690, A126 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.03137">arXiv:2407.03137</a> <span> [<a href="https://arxiv.org/pdf/2407.03137">pdf</a>, <a href="https://arxiv.org/format/2407.03137">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="Astrophysics of Galaxies">astro-ph.GA</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/10.1051/0004-6361/202449829">10.1051/0004-6361/202449829 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-Shooting ULLYSES: Massive stars at low metallicity. IV. Spectral analysis methods and exemplary results for O stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Sander%2C+A+A+C">A. A. C. Sander</a>, <a href="/search/astro-ph?searchtype=author&query=Bouret%2C+J+-">J. -C. Bouret</a>, <a href="/search/astro-ph?searchtype=author&query=Bernini-Peron%2C+M">M. Bernini-Peron</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">J. Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Backs%2C+F">F. Backs</a>, <a href="/search/astro-ph?searchtype=author&query=Berlanas%2C+S+R">S. R. Berlanas</a>, <a href="/search/astro-ph?searchtype=author&query=Bestenlehner%2C+J+M">J. M. Bestenlehner</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=Herrero%2C+A">A. Herrero</a>, <a href="/search/astro-ph?searchtype=author&query=Martins%2C+F">F. Martins</a>, <a href="/search/astro-ph?searchtype=author&query=Maryeva%2C+O">O. Maryeva</a>, <a href="/search/astro-ph?searchtype=author&query=Pauli%2C+D">D. Pauli</a>, <a href="/search/astro-ph?searchtype=author&query=Ramachandran%2C+V">V. Ramachandran</a>, <a href="/search/astro-ph?searchtype=author&query=Crowther%2C+P+A">P. A. Crowther</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez-Gonz%C3%A1lez%2C+V+M+A">V. M. A. G贸mez-Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Gormaz-Matamala%2C+A+C">A. C. Gormaz-Matamala</a>, <a href="/search/astro-ph?searchtype=author&query=Hamann%2C+W+-">W. -R. Hamann</a>, <a href="/search/astro-ph?searchtype=author&query=Hillier%2C+D+J">D. J. Hillier</a>, <a href="/search/astro-ph?searchtype=author&query=Kuiper%2C+R">R. Kuiper</a>, <a href="/search/astro-ph?searchtype=author&query=Larkin%2C+C+J+K">C. J. K. Larkin</a>, <a href="/search/astro-ph?searchtype=author&query=Lefever%2C+R+R">R. R. Lefever</a>, <a href="/search/astro-ph?searchtype=author&query=Mehner%2C+A">A. Mehner</a>, <a href="/search/astro-ph?searchtype=author&query=Najarro%2C+F">F. Najarro</a>, <a href="/search/astro-ph?searchtype=author&query=Oskinova%2C+L+M">L. M. Oskinova</a>, <a href="/search/astro-ph?searchtype=author&query=Sch%C3%B6sser%2C+E+C">E. C. Sch枚sser</a> , et al. (4 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="2407.03137v2-abstract-short" style="display: inline;"> CONTEXT: The spectral analysis of hot, massive stars is a fundamental astrophysical method to obtain their intrinsic properties and their feedback. Quantitative spectroscopy for hot, massive stars requires detailed numerical modeling of the atmosphere and an iterative treatment to obtain the best solution within a given framework. AIMS: We present an overview of different techniques for the quanti… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.03137v2-abstract-full').style.display = 'inline'; document.getElementById('2407.03137v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.03137v2-abstract-full" style="display: none;"> CONTEXT: The spectral analysis of hot, massive stars is a fundamental astrophysical method to obtain their intrinsic properties and their feedback. Quantitative spectroscopy for hot, massive stars requires detailed numerical modeling of the atmosphere and an iterative treatment to obtain the best solution within a given framework. AIMS: We present an overview of different techniques for the quantitative spectroscopy of hot stars employed within the X-Shooting ULLYSES collaboration, from grid-based approaches to tailored fits. By performing a blind test, we gain an overview about the similarities and differences of the resulting parameters. Our study aims to provide an overview of the parameter spread caused by different approaches. METHODS: For three different stars from the sample (SMC O5 star AzV 377, LMC O7 star Sk -69 50, and LMC O9 star Sk -66 171), we employ different atmosphere codes (CMFGEN, Fastwind, PoWR) and strategies to determine their best-fitting model. For our analyses, UV and optical spectra are used to derive the properties with some methods relying purely on optical data for comparison. To determine the overall spectral energy distribution, we further employ additional photometry from the literature. RESULTS: Effective temperatures for each of three sample stars agree within 3 kK while the differences in log g can be up to 0.2 dex. Luminosity differences of up to 0.1 dex result from different reddening assumptions, which seem to be larger for the methods employing a genetic algorithm. All sample stars are nitrogen-enriched. CONCLUSIONS: We find a reasonable agreement between the different methods. Tailored fitting tends to be able to minimize discrepancies obtained with more course or automatized treatments. UV spectral data is essential for the determination of realistic wind parameters. For one target (Sk -69 50), we find clear indications of an evolved status. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.03137v2-abstract-full').style.display = 'none'; document.getElementById('2407.03137v2-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 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">19+15 pages, 21+4 figures, accepted version (A&A 689, A30) including language editing, condensed abstract</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 689, A30 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.01267">arXiv:2405.01267</a> <span> [<a href="https://arxiv.org/pdf/2405.01267">pdf</a>, <a href="https://arxiv.org/ps/2405.01267">ps</a>, <a href="https://arxiv.org/format/2405.01267">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="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> X-Shooting ULLYSES: Massive stars at low metallicity -- V. Effect of metallicity on surface abundances of O stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Martins%2C+F">F. Martins</a>, <a href="/search/astro-ph?searchtype=author&query=Bouret%2C+J+-">J. -C. Bouret</a>, <a href="/search/astro-ph?searchtype=author&query=Hillier%2C+D+J">D. J. Hillier</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=Crowther%2C+P+A">P. A. Crowther</a>, <a href="/search/astro-ph?searchtype=author&query=Herrero%2C+A">A. Herrero</a>, <a href="/search/astro-ph?searchtype=author&query=Najarro%2C+F">F. Najarro</a>, <a href="/search/astro-ph?searchtype=author&query=Pauli%2C+D">D. Pauli</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">J. Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Ramachandran%2C+V">V. Ramachandran</a>, <a href="/search/astro-ph?searchtype=author&query=Sander%2C+A+A+C">A. A. C. Sander</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J+S">J. S. Vink</a>, <a href="/search/astro-ph?searchtype=author&query=collaboration%2C+t+X">the XshootU collaboration</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="2405.01267v1-abstract-short" style="display: inline;"> Massive stars rotate faster, on average, than lower mass stars. Stellar rotation triggers hydrodynamical instabilities which transport angular momentum and chemical species from the core to the surface. Models of high-mass stars that include these processes predict that chemical mixing is stronger at lower metallicity. We aim to test this prediction by comparing the surface abundances of massive s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.01267v1-abstract-full').style.display = 'inline'; document.getElementById('2405.01267v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.01267v1-abstract-full" style="display: none;"> Massive stars rotate faster, on average, than lower mass stars. Stellar rotation triggers hydrodynamical instabilities which transport angular momentum and chemical species from the core to the surface. Models of high-mass stars that include these processes predict that chemical mixing is stronger at lower metallicity. We aim to test this prediction by comparing the surface abundances of massive stars at different metallicities. We performed a spectroscopic analysis of single O stars in the Magellanic Clouds (MCs) based on the ULLYSES and XshootU surveys. We determined the fundamental parameters and helium, carbon, nitrogen, and oxygen surface abundances of 17 LMC and 17 SMC non-supergiant O6-9.5 stars. We complemented these determinations by literature results for additional MCs and also Galactic stars to increase the sample size and metallicity coverage. We investigated the differences in the surface chemical enrichment at different metallicities and compared them with predictions of three sets of evolutionary models. Surface abundances are consistent with CNO-cycle nucleosynthesis. The maximum surface nitrogen enrichment is stronger in MC stars than in Galactic stars. Nitrogen enrichment is also observed in stars with higher surface gravities in the SMC than in the Galaxy. This trend is predicted by models that incorporate chemical transport caused by stellar rotation. The distributions of projected rotational velocities in our samples are likely biased towards slow rotators. A metallicity dependence of surface abundances is demonstrated. The analysis of larger samples with an unbiased distribution of projected rotational velocities is required to better constrain the treatment of chemical mixing and angular momentum transport in massive single and binary stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.01267v1-abstract-full').style.display = 'none'; document.getElementById('2405.01267v1-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">15 pages + appendix. Accepted in Astronomy & Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.16987">arXiv:2402.16987</a> <span> [<a href="https://arxiv.org/pdf/2402.16987">pdf</a>, <a href="https://arxiv.org/format/2402.16987">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="Astrophysics of Galaxies">astro-ph.GA</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/10.1051/0004-6361/202347479">10.1051/0004-6361/202347479 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-Shooting ULLYSES: Massive Stars at low metallicity II. DR1: Advanced optical data products for the Magellanic Clouds </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Sana%2C+H">H. Sana</a>, <a href="/search/astro-ph?searchtype=author&query=Tramper%2C+F">F. Tramper</a>, <a href="/search/astro-ph?searchtype=author&query=Abdul-Masih%2C+M">M. Abdul-Masih</a>, <a href="/search/astro-ph?searchtype=author&query=Blomme%2C+R">R. Blomme</a>, <a href="/search/astro-ph?searchtype=author&query=Dsilva%2C+K">K. Dsilva</a>, <a href="/search/astro-ph?searchtype=author&query=Maravelias%2C+G">G. Maravelias</a>, <a href="/search/astro-ph?searchtype=author&query=Martins%2C+L">L. Martins</a>, <a href="/search/astro-ph?searchtype=author&query=Mehner%2C+A">A. Mehner</a>, <a href="/search/astro-ph?searchtype=author&query=Wofford%2C+A">A. Wofford</a>, <a href="/search/astro-ph?searchtype=author&query=Banyard%2C+G">G. Banyard</a>, <a href="/search/astro-ph?searchtype=author&query=Barbosa%2C+C+L">C. L. Barbosa</a>, <a href="/search/astro-ph?searchtype=author&query=Bestenlehner%2C+J">J. Bestenlehner</a>, <a href="/search/astro-ph?searchtype=author&query=Hawcroft%2C+C">C. Hawcroft</a>, <a href="/search/astro-ph?searchtype=author&query=Hillier%2C+D+J">D. John Hillier</a>, <a href="/search/astro-ph?searchtype=author&query=Todt%2C+H">H. Todt</a>, <a href="/search/astro-ph?searchtype=author&query=Larkin%2C+C+J+K">C. J. K. Larkin</a>, <a href="/search/astro-ph?searchtype=author&query=Mahy%2C+L">L. Mahy</a>, <a href="/search/astro-ph?searchtype=author&query=Najarro%2C+F">F. Najarro</a>, <a href="/search/astro-ph?searchtype=author&query=Ramachandran%2C+V">V. Ramachandran</a>, <a href="/search/astro-ph?searchtype=author&query=Ramirez-Tannus%2C+M+C">M. C. Ramirez-Tannus</a>, <a href="/search/astro-ph?searchtype=author&query=Rubio-Diez%2C+M+M">M. M. Rubio-Diez</a>, <a href="/search/astro-ph?searchtype=author&query=Sander%2C+A+A+C">A. A. C. Sander</a>, <a href="/search/astro-ph?searchtype=author&query=Shenar%2C+T">T. Shenar</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J+S">J. S. Vink</a>, <a href="/search/astro-ph?searchtype=author&query=Backs%2C+F">F. Backs</a> , et al. (12 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="2402.16987v1-abstract-short" style="display: inline;"> Using the medium resolution spectrograph X-shooter, spectra of 235 OB and Wolf-Rayet (WR) stars in sub-solar metallicity environments have been secured. [...]This second paper focuses on the optical observations of 232 Magellanic Clouds targets. It describes the uniform reduction of the UVB (300 - 560 nm) and VIS (550 - 1020 nm) XShootU data as well as the preparation of advanced data products [..… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.16987v1-abstract-full').style.display = 'inline'; document.getElementById('2402.16987v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.16987v1-abstract-full" style="display: none;"> Using the medium resolution spectrograph X-shooter, spectra of 235 OB and Wolf-Rayet (WR) stars in sub-solar metallicity environments have been secured. [...]This second paper focuses on the optical observations of 232 Magellanic Clouds targets. It describes the uniform reduction of the UVB (300 - 560 nm) and VIS (550 - 1020 nm) XShootU data as well as the preparation of advanced data products [...] . The data reduction of the raw data is based on the ESO CPL X-shooter pipeline. We paid particular attention to the determination of the response curves [...] We implemented slit-loss correction, absolute flux calibration, (semi-)automatic rectification to the continuum, and a correction for telluric lines. The spectra of individual epochs were corrected for the barycentric motion, re-sampled and co-added, and the spectra from the two arms were merged into a single flux calibrated spectrum covering the entire optical range with maximum signal-to-noise ratio. [...] We provide three types of data products: (i) two-dimensional spectra for each UVB and VIS exposure; (ii) one-dimensional UVB and VIS spectra before and after response-correction, as well as after applying various processing, including absolute flux calibration, telluric removal, normalisation and barycentric correction; and (iii) co-added flux-calibrated and rectified spectra over the full optical range, for which all available XShootU exposures were combined. For many of the targets, the final signal-to-noise ratio per resolution element is above 200 in both the UVB and the VIS co-added spectra. The reduced data and advanced scientific data products will be made available to the community upon publication of this paper. [...] <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.16987v1-abstract-full').style.display = 'none'; document.getElementById('2402.16987v1-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 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">22 pages, 19 figures; accepted for publication in Astronomy & Astrophysics. Links to online tables and databases will be included upon publication</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 688, A104 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.06376">arXiv:2305.06376</a> <span> [<a href="https://arxiv.org/pdf/2305.06376">pdf</a>, <a href="https://arxiv.org/format/2305.06376">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="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</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/10.1051/0004-6361/202245650">10.1051/0004-6361/202245650 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-Shooting ULLYSES: massive stars at low metallicity. I. Project Description </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J+S">Jorick S. Vink</a>, <a href="/search/astro-ph?searchtype=author&query=Mehner%2C+A">A. Mehner</a>, <a href="/search/astro-ph?searchtype=author&query=Crowther%2C+P+A">P. A. Crowther</a>, <a href="/search/astro-ph?searchtype=author&query=Fullerton%2C+A">A. Fullerton</a>, <a href="/search/astro-ph?searchtype=author&query=Garcia%2C+M">M. Garcia</a>, <a href="/search/astro-ph?searchtype=author&query=Martins%2C+F">F. Martins</a>, <a href="/search/astro-ph?searchtype=author&query=Morrell%2C+N">N. Morrell</a>, <a href="/search/astro-ph?searchtype=author&query=Oskinova%2C+L+M">L. M. Oskinova</a>, <a href="/search/astro-ph?searchtype=author&query=St-Louis%2C+N">N. St-Louis</a>, <a href="/search/astro-ph?searchtype=author&query=ud-Doula%2C+A">A. ud-Doula</a>, <a href="/search/astro-ph?searchtype=author&query=Sander%2C+A+A+C">A. A. C. Sander</a>, <a href="/search/astro-ph?searchtype=author&query=Sana%2C+H">H. Sana</a>, <a href="/search/astro-ph?searchtype=author&query=Bouret%2C+J+-">J. -C. Bouret</a>, <a href="/search/astro-ph?searchtype=author&query=Kubatova%2C+B">B. Kubatova</a>, <a href="/search/astro-ph?searchtype=author&query=Marchant%2C+P">P. Marchant</a>, <a href="/search/astro-ph?searchtype=author&query=Martins%2C+L+P">L. P. Martins</a>, <a href="/search/astro-ph?searchtype=author&query=Wofford%2C+A">A. Wofford</a>, <a href="/search/astro-ph?searchtype=author&query=van+Loon%2C+J+T">J. Th. van Loon</a>, <a href="/search/astro-ph?searchtype=author&query=Telford%2C+O+G">O. Grace Telford</a>, <a href="/search/astro-ph?searchtype=author&query=Gotberg%2C+Y">Y. Gotberg</a>, <a href="/search/astro-ph?searchtype=author&query=Bowman%2C+D+M">D. M. Bowman</a>, <a href="/search/astro-ph?searchtype=author&query=Erba%2C+C">C. Erba</a>, <a href="/search/astro-ph?searchtype=author&query=Kalari%2C+V+M">V. M. Kalari</a>, <a href="/search/astro-ph?searchtype=author&query=Abdul-Masih%2C+M">M. Abdul-Masih</a>, <a href="/search/astro-ph?searchtype=author&query=Alkousa%2C+T">T. Alkousa</a> , et al. (56 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="2305.06376v3-abstract-short" style="display: inline;"> Observations of individual massive stars, super-luminous supernovae, gamma-ray bursts, and gravitational-wave events involving spectacular black-hole mergers, indicate that the low-metallicity Universe is fundamentally different from our own Galaxy. Many transient phenomena will remain enigmatic until we achieve a firm understanding of the physics and evolution of massive stars at low metallicity… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.06376v3-abstract-full').style.display = 'inline'; document.getElementById('2305.06376v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.06376v3-abstract-full" style="display: none;"> Observations of individual massive stars, super-luminous supernovae, gamma-ray bursts, and gravitational-wave events involving spectacular black-hole mergers, indicate that the low-metallicity Universe is fundamentally different from our own Galaxy. Many transient phenomena will remain enigmatic until we achieve a firm understanding of the physics and evolution of massive stars at low metallicity (Z). The Hubble Space Telescope has devoted 500 orbits to observe 250 massive stars at low Z in the ultraviolet (UV) with the COS and STIS spectrographs under the ULLYSES program. The complementary ``X-Shooting ULLYSES'' (XShootU) project provides enhanced legacy value with high-quality optical and near-infrared spectra obtained with the wide-wavelength coverage X-shooter spectrograph at ESO's Very Large Telescope. We present an overview of the XShootU project, showing that combining ULLYSES UV and XShootU optical spectra is critical for the uniform determination of stellar parameters such as effective temperature, surface gravity, luminosity, and abundances, as well as wind properties such as mass-loss rates in function of Z. As uncertainties in stellar and wind parameters percolate into many adjacent areas of Astrophysics, the data and modelling of the XShootU project is expected to be a game-changer for our physical understanding of massive stars at low Z. To be able to confidently interpret James Webb Space Telescope (JWST) spectra of the first stellar generations, the individual spectra of low Z stars need to be understood, which is exactly where XShootU can deliver. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.06376v3-abstract-full').style.display = 'none'; document.getElementById('2305.06376v3-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">Accepted in A&A - 35 Pages, 12 Figures, 4 Tables, 2 Large Tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 675, A154 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.12165">arXiv:2303.12165</a> <span> [<a href="https://arxiv.org/pdf/2303.12165">pdf</a>, <a href="https://arxiv.org/format/2303.12165">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="Astrophysics of Galaxies">astro-ph.GA</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/10.1051/0004-6361/202245588">10.1051/0004-6361/202245588 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-Shooting ULLYSES: Massive stars at low metallicity. III. Terminal wind speeds of ULLYSES massive stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hawcroft%2C+C">C. Hawcroft</a>, <a href="/search/astro-ph?searchtype=author&query=Sana%2C+H">H. Sana</a>, <a href="/search/astro-ph?searchtype=author&query=Mahy%2C+L">L. Mahy</a>, <a href="/search/astro-ph?searchtype=author&query=Sundqvist%2C+J+O">J. O. Sundqvist</a>, <a href="/search/astro-ph?searchtype=author&query=de+Koter%2C+A">A. de Koter</a>, <a href="/search/astro-ph?searchtype=author&query=Crowther%2C+P+A">P. A. Crowther</a>, <a href="/search/astro-ph?searchtype=author&query=Bestenlehner%2C+J+M">J. M. Bestenlehner</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=David-Uraz%2C+A">A. David-Uraz</a>, <a href="/search/astro-ph?searchtype=author&query=Decin%2C+L">L. Decin</a>, <a href="/search/astro-ph?searchtype=author&query=Erba%2C+C">C. Erba</a>, <a href="/search/astro-ph?searchtype=author&query=Garcia%2C+M">M. Garcia</a>, <a href="/search/astro-ph?searchtype=author&query=Hamann%2C+W+-">W. -R. Hamann</a>, <a href="/search/astro-ph?searchtype=author&query=Herrero%2C+A">A. Herrero</a>, <a href="/search/astro-ph?searchtype=author&query=Ignace%2C+R">R. Ignace</a>, <a href="/search/astro-ph?searchtype=author&query=Kee%2C+N+D">N. D. Kee</a>, <a href="/search/astro-ph?searchtype=author&query=Kub%C3%A1tov%C3%A1%2C+B">B. Kub谩tov谩</a>, <a href="/search/astro-ph?searchtype=author&query=Lefever%2C+R">R. Lefever</a>, <a href="/search/astro-ph?searchtype=author&query=Moffat%2C+A">A. Moffat</a>, <a href="/search/astro-ph?searchtype=author&query=Najarro%2C+F">F. Najarro</a>, <a href="/search/astro-ph?searchtype=author&query=Oskinova%2C+L">L. Oskinova</a>, <a href="/search/astro-ph?searchtype=author&query=Pauli%2C+D">D. Pauli</a>, <a href="/search/astro-ph?searchtype=author&query=Prinja%2C+R">R. Prinja</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">J. Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Sander%2C+A+A+C">A. A. C. Sander</a> , et al. (4 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="2303.12165v2-abstract-short" style="display: inline;"> The winds of massive stars have an impact on stellar evolution and on the surrounding medium. The maximum speed reached by these outflows, the terminal wind speed, is a global wind parameter and an essential input for models of stellar atmospheres and feedback. With the arrival of the ULLYSES programme, a legacy UV spectroscopic survey with HST, we have the opportunity to quantify the wind speeds… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.12165v2-abstract-full').style.display = 'inline'; document.getElementById('2303.12165v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.12165v2-abstract-full" style="display: none;"> The winds of massive stars have an impact on stellar evolution and on the surrounding medium. The maximum speed reached by these outflows, the terminal wind speed, is a global wind parameter and an essential input for models of stellar atmospheres and feedback. With the arrival of the ULLYSES programme, a legacy UV spectroscopic survey with HST, we have the opportunity to quantify the wind speeds of massive stars at sub-solar metallicity (in the Large and Small Magellanic Clouds, 0.5Z and 0.2Z) at an unprecedented scale. We empirically quantify the wind speeds of a large sample of OB stars, including supergiants, giants, and dwarfs at sub-solar metallicity. Using these measurements, we investigate trends of terminal wind speed with a number of fundamental stellar parameters, namely effective temperature, metallicity, and surface escape velocity. We empirically determined the terminal wind speed for a sample of 149 OB stars in the Magellanic Clouds either by directly measuring the maximum velocity shift of the absorption component of the Civ 1548-1550 line profile, or by fitting synthetic spectra produced using the Sobolev with exact integration method. Stellar parameters were either collected from the literature, obtained using spectral-type calibrations, or predicted from evolutionary models. We find strong trends of terminal wind speed with effective temperature and surface escape speed when the wind is strong enough to cause a saturated P Cygni profile in Civ 1548-1550. We find evidence for a metallicity dependence on the terminal wind speed proportional to Z^0.22+-0.03 when we compared our results to previous Galactic studies. Our results suggest that effective temperature rather than surface escape speed should be used as a straightforward empirical prediction of terminal wind speed and that the observed metallicity dependence is steeper than suggested by earlier works. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.12165v2-abstract-full').style.display = 'none'; document.getElementById('2303.12165v2-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 21 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">21 pages, 16 figures, 8 tables. 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 688, A105 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.09374">arXiv:2303.09374</a> <span> [<a href="https://arxiv.org/pdf/2303.09374">pdf</a>, <a href="https://arxiv.org/format/2303.09374">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</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/10.1051/0004-6361/202245536">10.1051/0004-6361/202245536 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Extinction towards the cluster R136 in the Large Magellanic Cloud: An extinction law from the near-infrared to the ultraviolet </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">Sarah A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=de+Koter%2C+A">Alex de Koter</a>, <a href="/search/astro-ph?searchtype=author&query=Bestenlehner%2C+J+M">Joachim M. Bestenlehner</a>, <a href="/search/astro-ph?searchtype=author&query=Crowther%2C+P+A">Paul A. Crowther</a>, <a href="/search/astro-ph?searchtype=author&query=Kaper%2C+L">Lex Kaper</a>, <a href="/search/astro-ph?searchtype=author&query=Caballero-Nieves%2C+S+M">Saida M. Caballero-Nieves</a>, <a href="/search/astro-ph?searchtype=author&query=Gr%C3%A4fener%2C+G">G枚tz Gr盲fener</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="2303.09374v1-abstract-short" style="display: inline;"> The cluster R136 in the giant star-forming region 30 Doradus in the Large Magellanic Cloud (LMC) offers a unique opportunity to resolve a stellar population in a starburst-like environment. We obtain the near-infrared to ultraviolet extinction towards 50 stars in the core of R136, employing the `extinction without standards' method. To assure good fits over the full wavelength range, we combine an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.09374v1-abstract-full').style.display = 'inline'; document.getElementById('2303.09374v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.09374v1-abstract-full" style="display: none;"> The cluster R136 in the giant star-forming region 30 Doradus in the Large Magellanic Cloud (LMC) offers a unique opportunity to resolve a stellar population in a starburst-like environment. We obtain the near-infrared to ultraviolet extinction towards 50 stars in the core of R136, employing the `extinction without standards' method. To assure good fits over the full wavelength range, we combine and modify existing extinction laws. We detect a strong spatial gradient in the extinction properties across the core of R136, coinciding with a gradient in density of cold gas that is part of a molecular cloud lying northeast of the cluster. In line with previous measurements of R136 and the 30 Doradus region, we obtain a high total-to-relative extinction ($R_V = 4.38 \pm 0.87$). However, the high values of $R_V$ are accompanied by relatively strong extinction in the ultraviolet, contrary to what is observed for Galactic sightlines. The relatively strong ultraviolet extinction suggests that the properties of the dust towards R136 differ from those in the Milky Way. For $R_{V} \sim 4.4$, about three times fewer ultraviolet photons can escape from the ambient dust environment relative to the canonical Galactic value of $R_{V} \sim 3.1$ at the same $A_{V}$. Therefore, if dust in the R136 star-bursting environment is characteristic for cosmologically distant star-bursting regions, the escape fraction of ultraviolet photons from such regions is overestimated by a factor of three relative to the standard Milky Way assumption for the total-to-selective extinction. Furthermore, a comparison with average curves tailored to other regions of the LMC shows that large differences in ultraviolet extinction exist within this galaxy. Further investigation is required in order to decipher whether or not there is a relation between $R_V$ and ultraviolet extinction in the LMC. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.09374v1-abstract-full').style.display = 'none'; document.getElementById('2303.09374v1-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 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">Accepted for publication in A&A (18 pages, 12 figures)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 673, A132 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.07060">arXiv:2211.07060</a> <span> [<a href="https://arxiv.org/pdf/2211.07060">pdf</a>, <a href="https://arxiv.org/format/2211.07060">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="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> Spin-down and reduced mass loss in early-type stars with large-scale magnetic fields </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Keszthelyi%2C+Z">Z. Keszthelyi</a>, <a href="/search/astro-ph?searchtype=author&query=de+Koter%2C+A">A. de Koter</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B6tberg%2C+Y">Y. G枚tberg</a>, <a href="/search/astro-ph?searchtype=author&query=Meynet%2C+G">G. Meynet</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+V">V. Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Carrington%2C+M">M. Carrington</a>, <a href="/search/astro-ph?searchtype=author&query=David-Uraz%2C+A">A. David-Uraz</a>, <a href="/search/astro-ph?searchtype=author&query=Geen%2C+S+T">S. T. Geen</a>, <a href="/search/astro-ph?searchtype=author&query=Georgy%2C+C">C. Georgy</a>, <a href="/search/astro-ph?searchtype=author&query=Hirschi%2C+R">R. Hirschi</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">J. Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Ramalatswa%2C+K+J">K. J. Ramalatswa</a>, <a href="/search/astro-ph?searchtype=author&query=Shultz%2C+M+E">M. E. Shultz</a>, <a href="/search/astro-ph?searchtype=author&query=ud-Doula%2C+A">A. ud-Doula</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="2211.07060v1-abstract-short" style="display: inline;"> Magnetism can greatly impact the evolution of stars. In some stars with OBA spectral types there is direct evidence via the Zeeman effect for stable, large-scale magnetospheres, which lead to the spin-down of the stellar surface and reduced mass loss. So far, a comprehensive grid of stellar structure and evolution models accounting for these effects was lacking. For this reason, we computed and st… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.07060v1-abstract-full').style.display = 'inline'; document.getElementById('2211.07060v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.07060v1-abstract-full" style="display: none;"> Magnetism can greatly impact the evolution of stars. In some stars with OBA spectral types there is direct evidence via the Zeeman effect for stable, large-scale magnetospheres, which lead to the spin-down of the stellar surface and reduced mass loss. So far, a comprehensive grid of stellar structure and evolution models accounting for these effects was lacking. For this reason, we computed and studied models with two magnetic braking and two chemical mixing schemes in three metallicity environments with the MESA software instrument. We find notable differences between the subgrids, which affects the model predictions and thus the detailed characterisation of stars. We are able to quantify the impact of magnetic fields in terms of preventing quasi-chemically homogeneous evolution and producing slowly-rotating, nitrogen-enriched ("Group 2") stars. Our model grid is fully open access and open source. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.07060v1-abstract-full').style.display = 'none'; document.getElementById('2211.07060v1-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, 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">to appear in "Winds of Stars and Exoplanets" Proceedings IAUS 370, 2022, eds.: A.A. Vidotto, L. Fossati, J.S. Vink</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.06350">arXiv:2209.06350</a> <span> [<a href="https://arxiv.org/pdf/2209.06350">pdf</a>, <a href="https://arxiv.org/format/2209.06350">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="Astrophysics of Galaxies">astro-ph.GA</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/stac2598">10.1093/mnras/stac2598 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The effects of surface fossil magnetic fields on massive star evolution: IV. Grids of models at Solar, LMC, and SMC metallicities </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Keszthelyi%2C+Z">Z. Keszthelyi</a>, <a href="/search/astro-ph?searchtype=author&query=de+Koter%2C+A">A. de Koter</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B6tberg%2C+Y">Y. G枚tberg</a>, <a href="/search/astro-ph?searchtype=author&query=Meynet%2C+G">G. Meynet</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=Petit%2C+V">V. Petit</a>, <a href="/search/astro-ph?searchtype=author&query=Carrington%2C+M">M. Carrington</a>, <a href="/search/astro-ph?searchtype=author&query=David-Uraz%2C+A">A. David-Uraz</a>, <a href="/search/astro-ph?searchtype=author&query=Geen%2C+S+T">S. T. Geen</a>, <a href="/search/astro-ph?searchtype=author&query=Georgy%2C+C">C. Georgy</a>, <a href="/search/astro-ph?searchtype=author&query=Hirschi%2C+R">R. Hirschi</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">J. Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Ramalatswa%2C+K+J">K. J. Ramalatswa</a>, <a href="/search/astro-ph?searchtype=author&query=Shultz%2C+M+E">M. E. Shultz</a>, <a href="/search/astro-ph?searchtype=author&query=ud-Doula%2C+A">A. ud-Doula</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="2209.06350v2-abstract-short" style="display: inline;"> Magnetic fields can drastically change predictions of evolutionary models of massive stars via mass-loss quenching, magnetic braking, and efficient angular momentum transport, which we aim to quantify in this work. We use the MESA software instrument to compute an extensive main-sequence grid of stellar structure and evolution models, as well as isochrones, accounting for the effects attributed to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.06350v2-abstract-full').style.display = 'inline'; document.getElementById('2209.06350v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.06350v2-abstract-full" style="display: none;"> Magnetic fields can drastically change predictions of evolutionary models of massive stars via mass-loss quenching, magnetic braking, and efficient angular momentum transport, which we aim to quantify in this work. We use the MESA software instrument to compute an extensive main-sequence grid of stellar structure and evolution models, as well as isochrones, accounting for the effects attributed to a surface fossil magnetic field. The grid is densely populated in initial mass (3-60 M$_\odot$), surface equatorial magnetic field strength (0-50 kG), and metallicity (representative of the Solar neighbourhood and the Magellanic Clouds). We use two magnetic braking and two chemical mixing schemes and compare the model predictions for slowly-rotating, nitrogen-enriched ("Group 2") stars with observations in the Large Magellanic Cloud. We quantify a range of initial field strengths that allow for producing Group 2 stars and find that typical values (up to a few kG) lead to solutions. Between the subgrids, we find notable departures in surface abundances and evolutionary paths. In our magnetic models, chemical mixing is always less efficient compared to non-magnetic models due to the rapid spin-down. We identify that quasi-chemically homogeneous main sequence evolution by efficient mixing could be prevented by fossil magnetic fields. We recommend comparing this grid of evolutionary models with spectropolarimetric and spectroscopic observations with the goals of i) revisiting the derived stellar parameters of known magnetic stars, and ii) observationally constraining the uncertain magnetic braking and chemical mixing schemes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.06350v2-abstract-full').style.display = 'none'; document.getElementById('2209.06350v2-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> 28 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 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">Accepted for publication in MNRAS. A full reproduction package is available on Zenodo at https://doi.org/10.5281/zenodo.7069766</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.11080">arXiv:2202.11080</a> <span> [<a href="https://arxiv.org/pdf/2202.11080">pdf</a>, <a href="https://arxiv.org/format/2202.11080">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/10.1051/0004-6361/202142742">10.1051/0004-6361/202142742 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The R136 star cluster dissected with Hubble Space Telescope/STIS. III. The most massive stars and their clumped winds </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">Sarah A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=de+Koter%2C+A">Alex de Koter</a>, <a href="/search/astro-ph?searchtype=author&query=Bestenlehner%2C+J+M">Joachim M. Bestenlehner</a>, <a href="/search/astro-ph?searchtype=author&query=Crowther%2C+P+A">Paul A. Crowther</a>, <a href="/search/astro-ph?searchtype=author&query=Sundqvist%2C+J+O">Jon O. Sundqvist</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">Joachim Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Caballero-Nieves%2C+S+M">Saida M. Caballero-Nieves</a>, <a href="/search/astro-ph?searchtype=author&query=Abdul-Masih%2C+M">Michael Abdul-Masih</a>, <a href="/search/astro-ph?searchtype=author&query=Driessen%2C+F+A">Florian A. Driessen</a>, <a href="/search/astro-ph?searchtype=author&query=Garc%C3%ADa%2C+M">Miriam Garc铆a</a>, <a href="/search/astro-ph?searchtype=author&query=Geen%2C+S">Sam Geen</a>, <a href="/search/astro-ph?searchtype=author&query=Gr%C3%A4fener%2C+G">G枚tz Gr盲fener</a>, <a href="/search/astro-ph?searchtype=author&query=Hawcroft%2C+C">Calum Hawcroft</a>, <a href="/search/astro-ph?searchtype=author&query=Kaper%2C+L">Lex Kaper</a>, <a href="/search/astro-ph?searchtype=author&query=Keszthelyi%2C+Z">Zsolt Keszthelyi</a>, <a href="/search/astro-ph?searchtype=author&query=Langer%2C+N">Norbert Langer</a>, <a href="/search/astro-ph?searchtype=author&query=Sana%2C+H">Hugues Sana</a>, <a href="/search/astro-ph?searchtype=author&query=Schneider%2C+F+R+N">Fabian R. N. Schneider</a>, <a href="/search/astro-ph?searchtype=author&query=Shenar%2C+T">Tomer Shenar</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J+S">Jorick S. Vink</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="2202.11080v1-abstract-short" style="display: inline;"> Context: The star cluster R136 inside the LMC hosts a rich population of massive stars, including the most massive stars known. The strong stellar winds of these very luminous stars impact their evolution and the surrounding environment. We currently lack detailed knowledge of the wind structure that is needed to quantify this impact. Aims: To observationally constrain the stellar and wind propert… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.11080v1-abstract-full').style.display = 'inline'; document.getElementById('2202.11080v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.11080v1-abstract-full" style="display: none;"> Context: The star cluster R136 inside the LMC hosts a rich population of massive stars, including the most massive stars known. The strong stellar winds of these very luminous stars impact their evolution and the surrounding environment. We currently lack detailed knowledge of the wind structure that is needed to quantify this impact. Aims: To observationally constrain the stellar and wind properties of the massive stars in R136, in particular the parameters related to wind clumping. Methods: We simultaneously analyse optical and UV spectroscopy of 53 O-type and 3 WNh-stars using the FASTWIND model atmosphere code and a genetic algorithm. The models account for optically thick clumps and effects related to porosity and velocity-porosity, as well as a non-void interclump medium. Results: We obtain stellar parameters, surface abundances, mass-loss rates, terminal velocities and clumping characteristics and compare these to theoretical predictions and evolutionary models. The clumping properties include the density of the interclump medium and the velocity-porosity of the wind. For the first time, these characteristics are systematically measured for a wide range of effective temperatures and luminosities. Conclusions: We confirm a cluster age of 1.0-2.5 Myr and derive an initial stellar mass of $\geq 250 {\rm M}_\odot$ for the most massive star in our sample, R136a1. The winds of our sample stars are highly clumped, with an average clumping factor of $f_{\rm cl}=29\pm15$. We find tentative trends in the wind-structure parameters as a function of mass-loss rate, suggesting that the winds of stars with higher mass-loss rates are less clumped. We compare several theoretical predictions to the observed mass-loss rates and terminal velocities and find that none satisfactorily reproduces both quantities. The prescription of Krti膷ka & Kub谩t (2018) matches best the observed mass-loss rates. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.11080v1-abstract-full').style.display = 'none'; document.getElementById('2202.11080v1-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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 A&A; Appendix I will not be included in the published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 663, A36 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.08340">arXiv:2108.08340</a> <span> [<a href="https://arxiv.org/pdf/2108.08340">pdf</a>, <a href="https://arxiv.org/format/2108.08340">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="Astrophysics of Galaxies">astro-ph.GA</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/10.1051/0004-6361/202140603">10.1051/0004-6361/202140603 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Empirical mass-loss rates and clumping properties of Galactic early-type O supergiants </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hawcroft%2C+C">C. Hawcroft</a>, <a href="/search/astro-ph?searchtype=author&query=Sana%2C+H">H. Sana</a>, <a href="/search/astro-ph?searchtype=author&query=Mahy%2C+L">L. Mahy</a>, <a href="/search/astro-ph?searchtype=author&query=Sundqvist%2C+J+O">J. O. Sundqvist</a>, <a href="/search/astro-ph?searchtype=author&query=Abdul-Masih%2C+M">M. Abdul-Masih</a>, <a href="/search/astro-ph?searchtype=author&query=Bouret%2C+J+C">J. C. Bouret</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">S. A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=de+Koter%2C+A">A. de Koter</a>, <a href="/search/astro-ph?searchtype=author&query=Driessen%2C+F+A">F. A. Driessen</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">J. Puls</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="2108.08340v1-abstract-short" style="display: inline;"> We investigate the impact of optically thick clumping on stellar wind diagnostics in O supergiants and constrain wind parameters associated with porosity in velocity space. This is the first time the effects of optically thick clumping have been investigated for a sample of massive hot stars, using models including a full optically thick clumping description. We re-analyse spectroscopic observatio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.08340v1-abstract-full').style.display = 'inline'; document.getElementById('2108.08340v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.08340v1-abstract-full" style="display: none;"> We investigate the impact of optically thick clumping on stellar wind diagnostics in O supergiants and constrain wind parameters associated with porosity in velocity space. This is the first time the effects of optically thick clumping have been investigated for a sample of massive hot stars, using models including a full optically thick clumping description. We re-analyse spectroscopic observations of a sample of eight O supergiants. Using a genetic algorithm wrapper around the NLTE atmosphere code FASTWIND we obtain simultaneous fits to optical and UV spectra and determine photospheric and wind properties and surface abundances. We provide empirical constraints on a number of wind parameters including the clumping factors, mass-loss rates and terminal wind velocities. Additionally, we establish the first systematic empirical constraints on velocity filling factors and interclump densities. These parameters describe clump distribution in velocity-space and density of the interclump medium in physical-space, respectively. We observe a mass-loss rate reduction of a factor of 3.6 compared to theoretical predictions from Vink et al. (2000), and mass-loss rates within a factor 1.4 of predictions from Bj枚rklund et al. (2021). We confirm that including optically thick clumping allows simultaneous fitting of recombination lines and resonance lines, including the unsaturated UV phosphorus lines (Pv 1118-1128), without reducing the phosphorus abundance. We find that, on average, half of the wind velocity field is covered by dense clumps. We also find that these clumps are 25 times denser than the average wind, and that the interclump medium is 3-10 times less dense than the mean wind. The former result agrees well with theoretical predictions, the latter suggests that lateral filling-in of radially compressed gas might be critical for setting the scale of the rarefied interclump matter. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.08340v1-abstract-full').style.display = 'none'; document.getElementById('2108.08340v1-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 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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 for publication in A&A; 35 pages, 20 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 655, A67 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.07621">arXiv:2104.07621</a> <span> [<a href="https://arxiv.org/pdf/2104.07621">pdf</a>, <a href="https://arxiv.org/format/2104.07621">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/10.1051/0004-6361/202040195">10.1051/0004-6361/202040195 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraining the Overcontact Phase in Massive Binary Evolution I. Mixing in V382 Cyg, VFTS 352, and OGLE SMC-SC10 108086 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abdul-Masih%2C+M">Michael Abdul-Masih</a>, <a href="/search/astro-ph?searchtype=author&query=Sana%2C+H">Hugues Sana</a>, <a href="/search/astro-ph?searchtype=author&query=Hawcroft%2C+C">Calum Hawcroft</a>, <a href="/search/astro-ph?searchtype=author&query=Almeida%2C+L+A">Leonardo A. Almeida</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">Sarah A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=de+Mink%2C+S+E">Selma E. de Mink</a>, <a href="/search/astro-ph?searchtype=author&query=Justham%2C+S">Stephen Justham</a>, <a href="/search/astro-ph?searchtype=author&query=Langer%2C+N">Norbert Langer</a>, <a href="/search/astro-ph?searchtype=author&query=Mahy%2C+L">Laurent Mahy</a>, <a href="/search/astro-ph?searchtype=author&query=Marchant%2C+P">Pablo Marchant</a>, <a href="/search/astro-ph?searchtype=author&query=Menon%2C+A">Athira Menon</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">Joachim Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Sundqvist%2C+J">Jon Sundqvist</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="2104.07621v2-abstract-short" style="display: inline;"> As potential progenitors of several exotic phenomena including gravitational wave sources, magnetic stars, and Be stars, close massive binary systems probe a crucial area of the parameter space in massive star evolution. Despite the importance of these systems, large uncertainties regarding the nature and efficiency of the internal mixing mechanisms still exist. In this work, we aim to provide rob… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.07621v2-abstract-full').style.display = 'inline'; document.getElementById('2104.07621v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.07621v2-abstract-full" style="display: none;"> As potential progenitors of several exotic phenomena including gravitational wave sources, magnetic stars, and Be stars, close massive binary systems probe a crucial area of the parameter space in massive star evolution. Despite the importance of these systems, large uncertainties regarding the nature and efficiency of the internal mixing mechanisms still exist. In this work, we aim to provide robust observational constraints on the internal mixing processes by spectroscopically analyzing a sample of three massive overcontact binaries at different metallicities. Using optical phase-resolved spectroscopic data, we perform an atmosphere analysis using more traditional 1D techniques and using state-of-the-art 3D techniques. We compare and contrast the assumptions and results of each technique and investigate how the assumptions affect the final derived atmospheric parameters. We find that in all three cases, both components of system are highly overluminous indicating either efficient internal mixing of helium or previous non-conservative mass transfer. However, we do not find strong evidence of helium or CNO surface abundance changes usually associated with mixing. Additionally, we find that in unequal mass systems, the measured effective temperature and luminosity of the less massive component places it very close to the more massive component on the Hertzsprung-Russell diagram. These results were obtained independently using both of the techniques mentioned above, which suggests that these measurements are robust. The observed discrepancies between the temperature and the surface abundance measurements when compared to theoretical expectations indicate that unaccounted for additional physical mechanisms may be at play. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.07621v2-abstract-full').style.display = 'none'; document.getElementById('2104.07621v2-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 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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 for publication in A&A; 28 pages, 20 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/2009.05136">arXiv:2009.05136</a> <span> [<a href="https://arxiv.org/pdf/2009.05136">pdf</a>, <a href="https://arxiv.org/format/2009.05136">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="Astrophysics of Galaxies">astro-ph.GA</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/staa2801">10.1093/mnras/staa2801 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The R136 star cluster dissected with Hubble Space Telescope/STIS. II. Physical properties of the most massive stars in R136 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bestenlehner%2C+J+M">Joachim M. Bestenlehner</a>, <a href="/search/astro-ph?searchtype=author&query=Crowther%2C+P+A">Paul A. Crowther</a>, <a href="/search/astro-ph?searchtype=author&query=Caballero-Nieves%2C+S+M">Saida M. Caballero-Nieves</a>, <a href="/search/astro-ph?searchtype=author&query=Schneider%2C+F+R+N">Fabian R. N. Schneider</a>, <a href="/search/astro-ph?searchtype=author&query=Simon-Diaz%2C+S">Sergio Simon-Diaz</a>, <a href="/search/astro-ph?searchtype=author&query=Brands%2C+S+A">Sarah A. Brands</a>, <a href="/search/astro-ph?searchtype=author&query=de+Koter%2C+A">Alex de Koter</a>, <a href="/search/astro-ph?searchtype=author&query=Graefener%2C+G">Goetz Graefener</a>, <a href="/search/astro-ph?searchtype=author&query=Herrero%2C+A">Artemio Herrero</a>, <a href="/search/astro-ph?searchtype=author&query=Langer%2C+N">Norbert Langer</a>, <a href="/search/astro-ph?searchtype=author&query=Lennon%2C+D+J">Daniel J. Lennon</a>, <a href="/search/astro-ph?searchtype=author&query=Apellaniz%2C+J+M">Jesus Maiz Apellaniz</a>, <a href="/search/astro-ph?searchtype=author&query=Puls%2C+J">Joachim Puls</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J+S">Jorick S. Vink</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="2009.05136v1-abstract-short" style="display: inline;"> We present an optical analysis of 55 members of R136, the central cluster in the Tarantula Nebula of the Large Magellanic Cloud. Our sample was observed with STIS aboard the Hubble Space Telescope, is complete down to about 40\,$M_{\odot}$, and includes 7 very massive stars with masses over 100\,$M_{\odot}$. We performed a spectroscopic analysis to derive their physical properties. Using evolution… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.05136v1-abstract-full').style.display = 'inline'; document.getElementById('2009.05136v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.05136v1-abstract-full" style="display: none;"> We present an optical analysis of 55 members of R136, the central cluster in the Tarantula Nebula of the Large Magellanic Cloud. Our sample was observed with STIS aboard the Hubble Space Telescope, is complete down to about 40\,$M_{\odot}$, and includes 7 very massive stars with masses over 100\,$M_{\odot}$. We performed a spectroscopic analysis to derive their physical properties. Using evolutionary models we find that the initial mass function (IMF) of massive stars in R136 is suggestive of being top-heavy with a power-law exponent $纬\approx 2 \pm 0.3$, but steeper exponents cannot be excluded. The age of R136 lies between 1 and 2\,Myr with a median age of around 1.6\,Myr. Stars more luminous than $\log L/L_{\odot} = 6.3$ are helium enriched and their evolution is dominated by mass loss, but rotational mixing or some other form of mixing could be still required to explain the helium composition at the surface. Stars more massive than 40\,$M_{\odot}$ have larger spectroscopic than evolutionary masses. The slope of the wind-luminosity relation assuming unclumped stellar winds is $2.41\pm0.13$ which is steeper than usually obtained ($\sim 1.8$). The ionising ($\log Q_0\,[{\rm ph/s}] = 51.4$) and mechanical ($\log L_{\rm SW}\,[{\rm erg/s}] = 39.1$) output of R136 is dominated by the most massive stars ($>100\,M_{\odot}$). R136 contributes around a quarter of the ionising flux and around a fifth of the mechanical feedback to the overall budget of the Tarantula Nebula. For a census of massive stars of the Tarantula Nebula region we combined our results with the VLT-FLAMES Tarantula Survey plus other spectroscopic studies. We observe a lack of evolved Wolf-Rayet stars and luminous blue and red supergiants. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.05136v1-abstract-full').style.display = 'none'; document.getElementById('2009.05136v1-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 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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 for publication in MNRAS, 21 pages, 14 figures, 2 tables plus 33 pages of supplementary material</span> </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 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