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class="vector-toc-numb">2</span> <span>Light curves</span> </div> </a> <ul id="toc-Light_curves-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Discovery" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Discovery"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Discovery</span> </div> </a> <ul id="toc-Discovery-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Period-luminosity_relation" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Period-luminosity_relation"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Period-luminosity relation</span> </div> </a> <ul id="toc-Period-luminosity_relation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Small_amplitude_Cepheids" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Small_amplitude_Cepheids"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Small amplitude Cepheids</span> </div> </a> <ul id="toc-Small_amplitude_Cepheids-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Uncertainties_in_Cepheid_determined_distances" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Uncertainties_in_Cepheid_determined_distances"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Uncertainties in Cepheid determined distances</span> </div> </a> <ul id="toc-Uncertainties_in_Cepheid_determined_distances-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Examples" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Examples"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Examples</span> </div> </a> <ul id="toc-Examples-sublist" 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class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/C%C3%A9ph%C3%A9ide_classique" title="Céphéide classique – French" lang="fr" hreflang="fr" data-title="Céphéide classique" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EA%B3%A0%EC%A0%84%EC%A0%81_%EC%84%B8%ED%8E%98%EC%9D%B4%EB%93%9C_%EB%B3%80%EA%B4%91%EC%84%B1" title="고전적 세페이드 변광성 – Korean" lang="ko" hreflang="ko" data-title="고전적 세페이드 변광성" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%9A%D0%BB%D0%B0%D1%81%D1%81%D0%B8%D0%BA%D0%B0%D0%BB%D1%8B%D2%9B_%D1%86%D0%B5%D1%84%D0%B5%D0%B8%D0%B4%D1%82%D0%B5%D1%80" title="Классикалық цефеидтер – Kazakh" lang="kk" hreflang="kk" data-title="Классикалық цефеидтер" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%9A%D0%BB%D0%B0%D1%81%D0%B8%D1%87%D0%BD%D0%B0_%D0%BA%D0%B5%D1%84%D0%B5%D0%B8%D0%B4%D0%B0" title="Класична кефеида – Macedonian" lang="mk" hreflang="mk" data-title="Класична кефеида" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a 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typeof="mw:File/Thumb"><a href="/wiki/File:HR-vartype.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a4/HR-vartype.svg/400px-HR-vartype.svg.png" decoding="async" width="400" height="457" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a4/HR-vartype.svg/600px-HR-vartype.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a4/HR-vartype.svg/800px-HR-vartype.svg.png 2x" data-file-width="700" data-file-height="800" /></a><figcaption><a href="/wiki/Hertzsprung%E2%80%93Russell_diagram" title="Hertzsprung–Russell diagram">Hertzsprung–Russell diagram</a> showing the location of several types of <a href="/wiki/Variable_star" title="Variable star">variable stars</a> superimposed on a display of the different <a href="/wiki/Stellar_classification#Yerkes_spectral_classification" title="Stellar classification">luminosity classes</a>.</figcaption></figure> <p><b>Classical Cepheids</b> are a type of <a href="/wiki/Cepheid_variable" title="Cepheid variable">Cepheid variable</a> <a href="/wiki/Star" title="Star">star</a>. They are young, <a href="/wiki/Population_I" class="mw-redirect" title="Population I">population I</a> <a href="/wiki/Variable_stars" class="mw-redirect" title="Variable stars">variable stars</a> that exhibit regular radial <a href="/wiki/Stellar_pulsation" title="Stellar pulsation">pulsations</a> with periods of a few days to a few weeks and visual <a href="/wiki/Amplitude" title="Amplitude">amplitudes</a> ranging from a few tenths of a <a href="/wiki/Magnitude_(astronomy)" title="Magnitude (astronomy)">magnitude</a> up to about 2 magnitudes. Classical Cepheids are also known as <b>Population I Cepheids</b>, <b>Type I Cepheids</b>, and <b>Delta Cepheid variables</b>. </p><p>There exists a well-defined <a href="/wiki/Period-luminosity_relation" title="Period-luminosity relation">relationship</a> between a classical Cepheid variable's <a href="/wiki/Luminosity" title="Luminosity">luminosity</a> and pulsation period,<sup id="cite_ref-OGLE_4_1-0" class="reference"><a href="#cite_note-OGLE_4-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-OGLE_1_2-0" class="reference"><a href="#cite_note-OGLE_1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> securing Cepheids as viable <a href="/wiki/Standard_candle" class="mw-redirect" title="Standard candle">standard candles</a> for establishing the galactic and <a href="/wiki/Extragalactic_distance_scale" class="mw-redirect" title="Extragalactic distance scale">extragalactic distance scales</a>.<sup id="cite_ref-freedman2001_3-0" class="reference"><a href="#cite_note-freedman2001-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-tammannsandage2008_4-0" class="reference"><a href="#cite_note-tammannsandage2008-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-majaess2009_5-0" class="reference"><a href="#cite_note-majaess2009-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-freedman2010_6-0" class="reference"><a href="#cite_note-freedman2010-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Hubble_Space_Telescope" title="Hubble Space Telescope">Hubble Space Telescope</a> (HST) observations of classical Cepheid variables have enabled firmer constraints on <a href="/wiki/Hubble%27s_law" title="Hubble's law">Hubble's law</a>, which describes the expansion rate of the <a href="/wiki/Observable_Universe" class="mw-redirect" title="Observable Universe">observable Universe</a>.<sup id="cite_ref-freedman2001_3-1" class="reference"><a href="#cite_note-freedman2001-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-tammannsandage2008_4-1" class="reference"><a href="#cite_note-tammannsandage2008-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-freedman2010_6-1" class="reference"><a href="#cite_note-freedman2010-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-ngeow2006_7-0" class="reference"><a href="#cite_note-ngeow2006-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-macririess2009_8-0" class="reference"><a href="#cite_note-macririess2009-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> Classical Cepheids have also been used to clarify many characteristics of our galaxy, such as the local <a href="/wiki/Spiral_arm" title="Spiral arm">spiral arm</a> structure and the Sun's distance from the <a href="/wiki/Galactic_plane" title="Galactic plane">galactic plane</a>.<sup id="cite_ref-majaess2009_5-1" class="reference"><a href="#cite_note-majaess2009-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>Around 800 classical Cepheids are known in the <a href="/wiki/Milky_Way" title="Milky Way">Milky Way</a> galaxy, out of an expected total of over 6,000. Several thousand more are known in the <a href="/wiki/Magellanic_Clouds" title="Magellanic Clouds">Magellanic Clouds</a>, with more discovered in other galaxies;<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> the <a href="/wiki/Hubble_Space_Telescope" title="Hubble Space Telescope">Hubble Space Telescope</a> has identified some in <a href="/wiki/NGC_4603" title="NGC 4603">NGC 4603</a>, which is 100 million <a href="/wiki/Light_year" class="mw-redirect" title="Light year">light years</a> distant.<sup id="cite_ref-HST_NGC_4603_Cepheid_Distance_10-0" class="reference"><a href="#cite_note-HST_NGC_4603_Cepheid_Distance-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Properties">Properties</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Classical_Cepheid_variable&action=edit&section=1" title="Edit section: Properties"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Evolutionary_track_5m.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Evolutionary_track_5m.svg/220px-Evolutionary_track_5m.svg.png" decoding="async" width="220" height="204" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Evolutionary_track_5m.svg/330px-Evolutionary_track_5m.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/3b/Evolutionary_track_5m.svg/440px-Evolutionary_track_5m.svg.png 2x" data-file-width="1260" data-file-height="1167" /></a><figcaption>The evolutionary track of 5 <var>M</var><sub>☉</sub> star crossing the <a href="/wiki/Instability_strip" title="Instability strip">instability strip</a> during a helium burning <a href="/wiki/Blue_loop" title="Blue loop">blue loop</a></figcaption></figure> <p>Classical Cepheid variables are 4–20 times more massive than the Sun,<sup id="cite_ref-turner96_11-0" class="reference"><a href="#cite_note-turner96-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> and around 1,000 to 50,000 (over 200,000 for the unusual <a href="/wiki/V810_Centauri" title="V810 Centauri">V810 Centauri</a>) times more luminous.<sup id="cite_ref-turner10_12-0" class="reference"><a href="#cite_note-turner10-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> Spectroscopically they are bright giants or low luminosity supergiants of <a href="/wiki/Spectral_classification" class="mw-redirect" title="Spectral classification">spectral class</a> F6 – K2. The temperature and spectral type vary as they pulsate. Their radii are a few tens to a few hundred times that of the sun. More luminous Cepheids are cooler and larger and have longer periods. Along with the temperature changes their radii also change during each pulsation (e.g. by ~25% for the longer-period <a href="/wiki/L_Carinae" title="L Carinae">l Car</a>), resulting in brightness variations up to two magnitudes. The brightness changes are more pronounced at shorter wavelengths.<sup id="cite_ref-rodgers_13-0" class="reference"><a href="#cite_note-rodgers-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p><p>Cepheid variables may pulsate in a <a href="/wiki/Fundamental_mode" class="mw-redirect" title="Fundamental mode">fundamental mode</a>, the first <a href="/wiki/Overtone" title="Overtone">overtone</a>, or rarely a mixed mode. Pulsations in an overtone higher than first are rare but interesting.<sup id="cite_ref-OGLE_1_2-1" class="reference"><a href="#cite_note-OGLE_1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The majority of classical Cepheids are thought to be fundamental mode pulsators, although it is not easy to distinguish the mode from the shape of the light curve. Stars pulsating in an overtone are more luminous and larger than a fundamental mode pulsator with the same period.<sup id="cite_ref-bobo_14-0" class="reference"><a href="#cite_note-bobo-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p><p>When an <a href="/wiki/Intermediate_mass_star" class="mw-redirect" title="Intermediate mass star">intermediate mass star</a> (IMS) first evolves away from the <a href="/wiki/Main_sequence" title="Main sequence">main sequence</a>, it crosses the instability strip very rapidly while the hydrogen shell is still burning. When the helium core ignites in an IMS, it may execute a <a href="/wiki/Blue_loop" title="Blue loop">blue loop</a> and crosses the instability strip again, once while evolving to high temperatures and again evolving back towards the <a href="/wiki/Asymptotic_giant_branch" title="Asymptotic giant branch">asymptotic giant branch</a>. Stars more massive than about 8–12 <var>M</var><sub>☉</sub> start core helium burning before reaching the <a href="/wiki/Red-giant_branch" title="Red-giant branch">red-giant branch</a> and become <a href="/wiki/Red_supergiant" title="Red supergiant">red supergiants</a>, but may still execute a blue loop through the instability strip. The duration and even existence of blue loops is very sensitive to the mass, <a href="/wiki/Metallicity" title="Metallicity">metallicity</a>, and helium abundance of the star. In some cases, stars may cross the instability strip for a fourth and fifth time when helium shell burning starts.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (May 2016)">citation needed</span></a></i>]</sup> The rate of change of the period of a Cepheid variable, along with chemical abundances detectable in the spectrum, can be used to deduce which crossing a particular star is making.<sup id="cite_ref-svvul_15-0" class="reference"><a href="#cite_note-svvul-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> </p><p>Classical Cepheid variables were B type <a href="/wiki/Main_sequence" title="Main sequence">main-sequence stars</a> earlier than about B7, possibly late O stars, before they ran out of hydrogen in their cores. More massive and hotter stars develop into more luminous Cepheids with longer periods, although it is expected that young stars within our own galaxy, at near solar metallicity, will generally lose sufficient mass by the time they first reach the <a href="/wiki/Instability_strip" title="Instability strip">instability strip</a> that they will have periods of 50 days or less. Above a certain mass, 20–50 <var>M</var><sub>☉</sub> depending on metallicity, red supergiants will evolve back to blue supergiants rather than execute a blue loop, but they will do so as unstable <a href="/wiki/Yellow_hypergiant" title="Yellow hypergiant">yellow hypergiants</a> rather than regularly pulsating Cepheid variables. Very massive stars never cool sufficiently to reach the instability strip and do not ever become Cepheids. At low metallicity, for example in the Magellanic Clouds, stars can retain more mass and become more luminous Cepheids with longer periods.<sup id="cite_ref-turner10_12-1" class="reference"><a href="#cite_note-turner10-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Light_curves">Light curves</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Classical_Cepheid_variable&action=edit&section=2" title="Edit section: Light curves"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Delta_Cephei_lightcurve.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Delta_Cephei_lightcurve.jpg/220px-Delta_Cephei_lightcurve.jpg" decoding="async" width="220" height="116" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Delta_Cephei_lightcurve.jpg/330px-Delta_Cephei_lightcurve.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Delta_Cephei_lightcurve.jpg/440px-Delta_Cephei_lightcurve.jpg 2x" data-file-width="720" data-file-height="381" /></a><figcaption><a href="/wiki/Delta_Cephei" title="Delta Cephei">Delta Cephei</a> lightcurve</figcaption></figure> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Delta_cephei_ubvri_engle_2014.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Delta_cephei_ubvri_engle_2014.png/220px-Delta_cephei_ubvri_engle_2014.png" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Delta_cephei_ubvri_engle_2014.png/330px-Delta_cephei_ubvri_engle_2014.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Delta_cephei_ubvri_engle_2014.png/440px-Delta_cephei_ubvri_engle_2014.png 2x" data-file-width="2400" data-file-height="1800" /></a><figcaption>Phase-folded UBVRI <a href="/wiki/Light_curves" class="mw-redirect" title="Light curves">light curves</a> of Delta Cephei, prototype of the classical Cepheids, showing magnitude versus pulsation phase<sup id="cite_ref-engle2014_16-0" class="reference"><a href="#cite_note-engle2014-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup></figcaption></figure> <p>A Cepheid light curve is typically asymmetric with a rapid rise to maximum light followed by a slower fall to minimum (e.g. <a href="/wiki/Delta_Cephei" title="Delta Cephei">Delta Cephei</a>). This is due to the phase difference between the radius and temperature variations and is considered characteristic of a fundamental mode pulsator, the most common type of type I Cepheid. In some cases the smooth pseudo-sinusoidal light curve shows a "bump", a brief slowing of the decline or even a small rise in brightness, thought to be due to a resonance between the fundamental and second overtone. The bump is most commonly seen on the descending branch for stars with periods around 6 days (e.g. <a href="/wiki/Eta_Aquilae" title="Eta Aquilae">Eta Aquilae</a>). As the period increases, the location of the bump moves closer to the maximum and may cause a double maximum, or become indistinguishable from the primary maximum, for stars having periods around 10 days (e.g. <a href="/wiki/Zeta_Geminorum" title="Zeta Geminorum">Zeta Geminorum</a>). At longer periods the bump can be seen on the ascending branch of the light curve (e.g. <a href="/wiki/X_Cygni" title="X Cygni">X Cygni</a>),<sup id="cite_ref-Kovtyukh_et_al_2005_17-0" class="reference"><a href="#cite_note-Kovtyukh_et_al_2005-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> but for period longer than 20 days the resonance disappears. </p><p>A minority of classical Cepheids show nearly symmetric sinusoidal light curves. These are referred to as s-Cepheids, usually have lower amplitudes, and commonly have short periods. The majority of these are thought to be first overtone (e.g. <a href="/wiki/X_Sagittarii" title="X Sagittarii">X Sagittarii</a>), or higher, pulsators, although some unusual stars apparently pulsating in the fundamental mode also show this shape of light curve (e.g. <a href="/wiki/S_Vulpeculae" title="S Vulpeculae">S Vulpeculae</a>). Stars pulsating in the first overtone are expected to only occur with short periods in our galaxy, although they may have somewhat longer periods at lower metallicity, for example in the Magellanic Clouds. Higher overtone pulsators and Cepheids pulsating in two overtones at the same time are also more common in the Magellanic Clouds, and they usually have low amplitude somewhat irregular light curves.<sup id="cite_ref-OGLE_1_2-2" class="reference"><a href="#cite_note-OGLE_1-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-OGLE_7_18-0" class="reference"><a href="#cite_note-OGLE_7-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Discovery">Discovery</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Classical_Cepheid_variable&action=edit&section=3" title="Edit section: Discovery"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:PSM_V69_D184_Light_curves_of_variable_stars.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/1/15/PSM_V69_D184_Light_curves_of_variable_stars.png/220px-PSM_V69_D184_Light_curves_of_variable_stars.png" decoding="async" width="220" height="116" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/15/PSM_V69_D184_Light_curves_of_variable_stars.png/330px-PSM_V69_D184_Light_curves_of_variable_stars.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/15/PSM_V69_D184_Light_curves_of_variable_stars.png/440px-PSM_V69_D184_Light_curves_of_variable_stars.png 2x" data-file-width="1676" data-file-height="884" /></a><figcaption>Historical light curves of <a href="/wiki/W_Sagittarii" title="W Sagittarii">W Sagittarii</a> and <a href="/wiki/Eta_Aquilae" title="Eta Aquilae">Eta Aquilae</a></figcaption></figure><p>On September 10, 1784 <a href="/wiki/Edward_Pigott" title="Edward Pigott">Edward Pigott</a> detected the variability of <a href="/wiki/Eta_Aquilae" title="Eta Aquilae">Eta Aquilae</a>, the first known representative of the class of classical Cepheid variables. However, the namesake for classical Cepheids is the star <a href="/wiki/Delta_Cephei" title="Delta Cephei">Delta Cephei</a>, discovered to be variable by <a href="/wiki/John_Goodricke" title="John Goodricke">John Goodricke</a> a month later.<sup id="cite_ref-hoskin_19-0" class="reference"><a href="#cite_note-hoskin-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> Delta Cephei is also of particular importance as a calibrator for the period-luminosity relation since its distance is among the most precisely established for a Cepheid, thanks in part to its membership in a <a href="/wiki/Star_cluster" title="Star cluster">star cluster</a><sup id="cite_ref-dezeeuw1999_20-0" class="reference"><a href="#cite_note-dezeeuw1999-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-majaess2012_21-0" class="reference"><a href="#cite_note-majaess2012-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> and the availability of precise <a href="/wiki/Hubble_Space_Telescope" title="Hubble Space Telescope">Hubble Space Telescope</a> and <a href="/wiki/Hipparcos" title="Hipparcos">Hipparcos</a> parallaxes.<sup id="cite_ref-benedict2002_22-0" class="reference"><a href="#cite_note-benedict2002-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p><div class="mw-heading mw-heading2"><h2 id="Period-luminosity_relation">Period-luminosity relation</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Classical_Cepheid_variable&action=edit&section=4" title="Edit section: Period-luminosity relation"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Period-luminosity_relation" title="Period-luminosity relation">Period-luminosity relation</a></div> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Period-Luminosity_Relation_for_Cepheids.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Period-Luminosity_Relation_for_Cepheids.png/220px-Period-Luminosity_Relation_for_Cepheids.png" decoding="async" width="220" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Period-Luminosity_Relation_for_Cepheids.png/330px-Period-Luminosity_Relation_for_Cepheids.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Period-Luminosity_Relation_for_Cepheids.png/440px-Period-Luminosity_Relation_for_Cepheids.png 2x" data-file-width="1800" data-file-height="1200" /></a><figcaption>The two Period-Luminosity Characteristics of Classic and Type II Cepheids</figcaption></figure> <p>A classical Cepheid's luminosity is directly related to its period of variation. The longer the pulsation period, the more luminous the star. The period-luminosity relation for classical Cepheids was discovered in 1908 by <a href="/wiki/Henrietta_Swan_Leavitt" title="Henrietta Swan Leavitt">Henrietta Swan Leavitt</a> in an investigation of thousands of variable stars in the <a href="/wiki/Magellanic_Clouds" title="Magellanic Clouds">Magellanic Clouds</a>.<sup id="cite_ref-leavitt_23-0" class="reference"><a href="#cite_note-leavitt-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> She published it in 1912<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> with further evidence. Once the period-luminosity relation is calibrated, the luminosity of a given Cepheid whose period is known can be established. Their distance is then found from their apparent brightness. The period-luminosity relation has been calibrated by many astronomers throughout the twentieth century, beginning with <a href="/wiki/Ejnar_Hertzsprung" title="Ejnar Hertzsprung">Hertzsprung</a>.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> Calibrating the period-luminosity relation has been problematic; however, a firm Galactic calibration was established by Benedict et al. 2007 using precise HST parallaxes for 10 nearby classical Cepheids.<sup id="cite_ref-benedict2007_26-0" class="reference"><a href="#cite_note-benedict2007-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> Also, in 2008, <a href="/wiki/European_Southern_Observatory" title="European Southern Observatory">ESO</a> astronomers estimated with a precision within 1% the distance to the Cepheid <a href="/wiki/RS_Puppis" title="RS Puppis">RS Puppis</a>, using <a href="/wiki/Light_echo" title="Light echo">light echos</a> from a nebula in which it is embedded.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> However, that latter finding has been actively debated in the literature.<sup id="cite_ref-Bond_2009_28-0" class="reference"><a href="#cite_note-Bond_2009-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> </p><p>The following experimental <a href="/wiki/Correlation" title="Correlation">correlations</a> between a Population I Cepheid's period <i>P</i> and its mean <a href="/wiki/Absolute_magnitude" title="Absolute magnitude">absolute magnitude</a> <i>M</i><sub>v</sub> was established from <a href="/wiki/Hubble_Space_Telescope" title="Hubble Space Telescope">Hubble Space Telescope</a> <a href="/wiki/Trigonometric_parallax" class="mw-redirect" title="Trigonometric parallax">trigonometric parallaxes</a> for 10 nearby Cepheids: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle M_{\mathrm {v} }=(-2.43\pm 0.12)\left(\log _{10}P-1\right)-(4.05\pm 0.02)\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>M</mi> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mi mathvariant="normal">v</mi> </mrow> </mrow> </msub> <mo>=</mo> <mo stretchy="false">(</mo> <mo>−</mo> <mn>2.43</mn> <mo>±</mo> <mn>0.12</mn> <mo stretchy="false">)</mo> <mrow> <mo>(</mo> <mrow> <msub> <mi>log</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>10</mn> </mrow> </msub> <mo>⁡</mo> <mi>P</mi> <mo>−</mo> <mn>1</mn> </mrow> <mo>)</mo> </mrow> <mo>−</mo> <mo stretchy="false">(</mo> <mn>4.05</mn> <mo>±</mo> <mn>0.02</mn> <mo stretchy="false">)</mo> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle M_{\mathrm {v} }=(-2.43\pm 0.12)\left(\log _{10}P-1\right)-(4.05\pm 0.02)\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/5297fcc220eede544b4896bfcd657070e82f5f43" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:50.504ex; height:2.843ex;" alt="{\displaystyle M_{\mathrm {v} }=(-2.43\pm 0.12)\left(\log _{10}P-1\right)-(4.05\pm 0.02)\,}"></span><sup id="cite_ref-benedict2007_26-1" class="reference"><a href="#cite_note-benedict2007-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup></dd></dl> <p>with <i>P</i> measured in days. </p><p>The following relations can also be used to calculate the distance <i>d</i> to classical Cepheids: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 5\log _{10}{d}=V+3.34\log _{10}{P}-2.45(V-I)+10.52\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mn>5</mn> <msub> <mi>log</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>10</mn> </mrow> </msub> <mo>⁡</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> <mo>=</mo> <mi>V</mi> <mo>+</mo> <mn>3.34</mn> <msub> <mi>log</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>10</mn> </mrow> </msub> <mo>⁡</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>P</mi> </mrow> <mo>−</mo> <mn>2.45</mn> <mo stretchy="false">(</mo> <mi>V</mi> <mo>−</mo> <mi>I</mi> <mo stretchy="false">)</mo> <mo>+</mo> <mn>10.52</mn> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle 5\log _{10}{d}=V+3.34\log _{10}{P}-2.45(V-I)+10.52\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/fd36c9398d89bcdf3ae837f4e40ddbf0e97f6171" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:50.336ex; height:2.843ex;" alt="{\displaystyle 5\log _{10}{d}=V+3.34\log _{10}{P}-2.45(V-I)+10.52\,}"></span><sup id="cite_ref-benedict2007_26-2" class="reference"><a href="#cite_note-benedict2007-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup></dd></dl> <p>or </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle 5\log _{10}{d}=V+3.37\log _{10}{P}-2.55(V-I)+10.48\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mn>5</mn> <msub> <mi>log</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>10</mn> </mrow> </msub> <mo>⁡</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>d</mi> </mrow> <mo>=</mo> <mi>V</mi> <mo>+</mo> <mn>3.37</mn> <msub> <mi>log</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>10</mn> </mrow> </msub> <mo>⁡</mo> <mrow class="MJX-TeXAtom-ORD"> <mi>P</mi> </mrow> <mo>−</mo> <mn>2.55</mn> <mo stretchy="false">(</mo> <mi>V</mi> <mo>−</mo> <mi>I</mi> <mo stretchy="false">)</mo> <mo>+</mo> <mn>10.48</mn> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle 5\log _{10}{d}=V+3.37\log _{10}{P}-2.55(V-I)+10.48\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/526f0fdd7f6f74dab7c9a32b354ad91fb849f972" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:50.336ex; height:2.843ex;" alt="{\displaystyle 5\log _{10}{d}=V+3.37\log _{10}{P}-2.55(V-I)+10.48\,}"></span><sup id="cite_ref-majaess2011_29-0" class="reference"><a href="#cite_note-majaess2011-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup></dd></dl> <p><i>I</i> and <i>V</i> represent near infrared and visual apparent mean magnitudes, respectively. The distance <i>d</i> is in <a href="/wiki/Parsec" title="Parsec">parsecs</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Small_amplitude_Cepheids">Small amplitude Cepheids</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Classical_Cepheid_variable&action=edit&section=5" title="Edit section: Small amplitude Cepheids"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Classical Cepheid variables with visual amplitudes below 0.5 magnitudes, almost symmetrical sinusoidal light curves, and short periods, have been defined as a separate group called small amplitude Cepheids. They receive the acronym DCEPS in the GCVS. Periods are generally less than 7 days, although the exact cutoff is still debated.<sup id="cite_ref-gcvs_30-0" class="reference"><a href="#cite_note-gcvs-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> The term s-Cepheid is used for short period small amplitude Cepheids with sinusoidal light curves that are considered to be first overtone pulsators. They are found near the red edge of the instability strip. Some authors use s-Cepheid as a synonym for the small amplitude DECPS stars, while others prefer to restrict it only to first overtone stars.<sup id="cite_ref-turner_31-0" class="reference"><a href="#cite_note-turner-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-antonello_32-0" class="reference"><a href="#cite_note-antonello-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> </p><p>Small amplitude Cepheids (DCEPS) include <a href="/wiki/Polaris" title="Polaris">Polaris</a> and <a href="/wiki/FF_Aquilae" title="FF Aquilae">FF Aquilae</a>, although both may be pulsating in the fundamental mode. Confirmed first overtone pulsators include <a href="/wiki/BG_Crucis" title="BG Crucis">BG Crucis</a> and <a href="/wiki/BP_Circini" title="BP Circini">BP Circini</a>.<sup id="cite_ref-usenko_33-0" class="reference"><a href="#cite_note-usenko-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-evans_34-0" class="reference"><a href="#cite_note-evans-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Uncertainties_in_Cepheid_determined_distances">Uncertainties in Cepheid determined distances</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Classical_Cepheid_variable&action=edit&section=6" title="Edit section: Uncertainties in Cepheid determined distances"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Chief among the uncertainties tied to the Cepheid distance scale are: the nature of the period-luminosity relation in various passbands, the impact of <a href="/wiki/Metallicity" title="Metallicity">metallicity</a> on both the zero-point and slope of those relations, and the effects of photometric contamination (blending) and a changing (typically unknown) extinction law on classical Cepheid distances. All these topics are actively debated in the literature.<sup id="cite_ref-tammannsandage2008_4-2" class="reference"><a href="#cite_note-tammannsandage2008-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-ngeow2006_7-1" class="reference"><a href="#cite_note-ngeow2006-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-turner10_12-2" class="reference"><a href="#cite_note-turner10-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-stanekudalski1999_36-0" class="reference"><a href="#cite_note-stanekudalski1999-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-udalski2001_37-0" class="reference"><a href="#cite_note-udalski2001-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-macri2006_38-0" class="reference"><a href="#cite_note-macri2006-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-bono2008_39-0" class="reference"><a href="#cite_note-bono2008-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-majaess2009b_40-0" class="reference"><a href="#cite_note-majaess2009b-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-madore2009_41-0" class="reference"><a href="#cite_note-madore2009-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-scowcroft2009_42-0" class="reference"><a href="#cite_note-scowcroft2009-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-majaess2010_43-0" class="reference"><a href="#cite_note-majaess2010-43"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup> </p><p>These unresolved matters have resulted in cited values for the <a href="/wiki/Hubble_constant" class="mw-redirect" title="Hubble constant">Hubble constant</a> ranging between 60 km/s/Mpc and 80 km/s/Mpc.<sup id="cite_ref-freedman2001_3-2" class="reference"><a href="#cite_note-freedman2001-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-tammannsandage2008_4-3" class="reference"><a href="#cite_note-tammannsandage2008-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-freedman2010_6-2" class="reference"><a href="#cite_note-freedman2010-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-ngeow2006_7-2" class="reference"><a href="#cite_note-ngeow2006-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-macririess2009_8-1" class="reference"><a href="#cite_note-macririess2009-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> Resolving this discrepancy is one of the foremost problems in astronomy since the cosmological parameters of the Universe may be constrained by supplying a precise value of the Hubble constant.<sup id="cite_ref-freedman2010_6-3" class="reference"><a href="#cite_note-freedman2010-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-macririess2009_8-2" class="reference"><a href="#cite_note-macririess2009-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Examples">Examples</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Classical_Cepheid_variable&action=edit&section=7" title="Edit section: Examples"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Several classical Cepheids have variations that can be recorded with night-by-night, trained <a href="/wiki/Bright_Star_Catalogue" title="Bright Star Catalogue">naked eye</a> observation, including the prototype <a href="/wiki/Delta_Cephei" title="Delta Cephei">Delta Cephei</a> in the far north, <a href="/wiki/Zeta_Geminorum" title="Zeta Geminorum">Zeta Geminorum</a> and <a href="/wiki/Eta_Aquilae" title="Eta Aquilae">Eta Aquilae</a> ideal for observation around the tropics (near the ecliptic and thus zodiac) and in the far south <a href="/wiki/Beta_Doradus" title="Beta Doradus">Beta Doradus</a>. The closest class member is the North Star (<a href="/wiki/Polaris" title="Polaris">Polaris</a>) whose distance is debated and whose present variability is approximately 0.05 of a magnitude.<sup id="cite_ref-freedman2010_6-4" class="reference"><a href="#cite_note-freedman2010-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable sortable" style="font-size:90%;"> <tbody><tr style="background:#efefef;"> <th style="width:10%;"><b>Designation (name)</b> </th> <th style="width:10%;"><b>Constellation</b> </th> <th style="width:15%;"><b>Discovery</b> </th> <th style="width:10%;"><i>Maximum <a href="/wiki/Apparent_magnitude" title="Apparent magnitude">Apparent magnitude</a></i> (m<sub>V</sub>)<sup id="cite_ref-berdnikov_44-0" class="reference"><a href="#cite_note-berdnikov-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> </th> <th style="width:10%;"><i>Minimum <a href="/wiki/Apparent_magnitude" title="Apparent magnitude">Apparent magnitude</a></i> (m<sub>V</sub>)<sup id="cite_ref-berdnikov_44-1" class="reference"><a href="#cite_note-berdnikov-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> </th> <th style="width:15%;"><b>Period</b> (days)<sup id="cite_ref-berdnikov_44-2" class="reference"><a href="#cite_note-berdnikov-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> </th> <th style="width:15%;"><b>Spectral class</b> </th> <th style="width:15%;"><b>Comment</b> </th></tr> <tr> <td><a href="/wiki/Eta_Aquilae" title="Eta Aquilae">η Aql</a> </td> <td><a href="/wiki/Aquila_(constellation)" title="Aquila (constellation)">Aquila</a> </td> <td><a href="/wiki/Edward_Pigott" title="Edward Pigott">Edward Pigott</a>, 1784 </td> <td>3<sup>m</sup>.48 </td> <td>4<sup>m</sup>.39 </td> <td>07.17664 </td> <td>F6 Ibv </td> <td>  </td></tr> <tr> <td><a href="/wiki/FF_Aquilae" title="FF Aquilae">FF Aql</a> </td> <td><a href="/wiki/Aquila_(constellation)" title="Aquila (constellation)">Aquila</a> </td> <td><a href="/wiki/Charles_Morse_Huffer" title="Charles Morse Huffer">Charles Morse Huffer</a>, 1927 </td> <td>5<sup>m</sup>.18 </td> <td>5<sup>m</sup>.68 </td> <td>04.47 </td> <td>F5Ia-F8Ia </td> <td>  </td></tr> <tr> <td><a href="/wiki/TT_Aquilae" title="TT Aquilae">TT Aql</a> </td> <td><a href="/wiki/Aquila_(constellation)" title="Aquila (constellation)">Aquila</a> </td> <td> </td> <td>6<sup>m</sup>.46 </td> <td>7<sup>m</sup>.7 </td> <td>13.7546 </td> <td>F6-G5 </td> <td>  </td></tr> <tr> <td><a href="/wiki/U_Aquilae" title="U Aquilae">U Aql</a> </td> <td><a href="/wiki/Aquila_(constellation)" title="Aquila (constellation)">Aquila</a> </td> <td> </td> <td>6<sup>m</sup>.08 </td> <td>6<sup>m</sup>.86 </td> <td>07.02393 </td> <td>F5I-II-G1 </td> <td>  </td></tr> <tr> <td><a href="/wiki/T_Antliae" title="T Antliae">T Ant</a> </td> <td><a href="/wiki/Antlia" title="Antlia">Antlia</a> </td> <td> </td> <td>5<sup>m</sup>.00 </td> <td>5<sup>m</sup>.82 </td> <td>05.898 </td> <td>G5 </td> <td>possibly has unseen companion. Previously thought to be a type II Cepheid<sup id="cite_ref-45" class="reference"><a href="#cite_note-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> </td></tr> <tr> <td><a href="/wiki/RT_Aurigae" title="RT Aurigae">RT Aur</a> </td> <td><a href="/wiki/Auriga_(constellation)" class="mw-redirect" title="Auriga (constellation)">Auriga</a> </td> <td> </td> <td>5<sup>m</sup>.00 </td> <td>5<sup>m</sup>.82 </td> <td>03.73 </td> <td>F8Ibv </td> <td>  </td></tr> <tr> <td><a href="/wiki/HD_84810" title="HD 84810">l Car</a> </td> <td><a href="/wiki/Carina_(constellation)" title="Carina (constellation)">Carina</a> </td> <td>  </td> <td>3<sup>m</sup>.28 </td> <td>4<sup>m</sup>.18 </td> <td>35.53584 </td> <td>G5 Iab/Ib </td> <td>  </td></tr> <tr> <td><a href="/wiki/Delta_Cephei" title="Delta Cephei">δ Cep</a> </td> <td><a href="/wiki/Cepheus_(constellation)" title="Cepheus (constellation)">Cepheus</a> </td> <td><a href="/wiki/John_Goodricke" title="John Goodricke">John Goodricke</a>, 1784 </td> <td>3<sup>m</sup>.48 </td> <td>4<sup>m</sup>.37 </td> <td>05.36634 </td> <td>F5Ib-G2Ib </td> <td>double star, visible in binoculars </td></tr> <tr> <td><a href="/wiki/AX_Circini" title="AX Circini">AX Cir</a> </td> <td><a href="/wiki/Circinus" title="Circinus">Circinus</a> </td> <td>  </td> <td>5<sup>m</sup>.65 </td> <td>6<sup>m</sup>.09 </td> <td>05.273268 </td> <td>F2-G2II </td> <td>spectroscopic binary with 5 <a href="/wiki/Solar_mass" title="Solar mass"><var>M</var><sub>☉</sub></a> B6 companion </td></tr> <tr> <td><a href="/wiki/BP_Circini" title="BP Circini">BP Cir</a> </td> <td><a href="/wiki/Circinus" title="Circinus">Circinus</a> </td> <td>  </td> <td>7<sup>m</sup>.31 </td> <td>7<sup>m</sup>.71 </td> <td>02.39810 </td> <td>F2/3II-F6 </td> <td>spectroscopic binary with 4.7 <a href="/wiki/Solar_mass" title="Solar mass"><var>M</var><sub>☉</sub></a> B6 companion </td></tr> <tr> <td><a href="/wiki/BG_Crucis" title="BG Crucis">BG Cru</a> </td> <td><a href="/wiki/Crux" title="Crux">Crux</a> </td> <td>  </td> <td>5<sup>m</sup>.34 </td> <td>5<sup>m</sup>.58 </td> <td>03.3428 </td> <td>F5Ib-G0p </td> <td>  </td></tr> <tr> <td><a href="/wiki/R_Crucis" title="R Crucis">R Cru</a> </td> <td><a href="/wiki/Crux" title="Crux">Crux</a> </td> <td>  </td> <td>6<sup>m</sup>.40 </td> <td>7<sup>m</sup>.23 </td> <td>05.82575 </td> <td>F7Ib/II </td> <td>  </td></tr> <tr> <td><a href="/wiki/S_Crucis" title="S Crucis">S Cru</a> </td> <td><a href="/wiki/Crux" title="Crux">Crux</a> </td> <td>  </td> <td>6<sup>m</sup>.22 </td> <td>6<sup>m</sup>.92 </td> <td>04.68997 </td> <td>F6-G1Ib-II </td> <td>  </td></tr> <tr> <td><a href="/wiki/T_Crucis" title="T Crucis">T Cru</a> </td> <td><a href="/wiki/Crux" title="Crux">Crux</a> </td> <td>  </td> <td>6<sup>m</sup>.32 </td> <td>6<sup>m</sup>.83 </td> <td>06.73331 </td> <td>F6-G2Ib </td> <td>  </td></tr> <tr> <td><a href="/wiki/X_Cygni" title="X Cygni">X Cyg</a> </td> <td><a href="/wiki/Cygnus_(constellation)" title="Cygnus (constellation)">Cygnus</a> </td> <td>  </td> <td>5<sup>m</sup>.85 </td> <td>6<sup>m</sup>.91 </td> <td>16.38633 </td> <td>G8Ib<sup id="cite_ref-tomasella_46-0" class="reference"><a href="#cite_note-tomasella-46"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup> </td> <td>  </td></tr> <tr> <td><a href="/wiki/SU_Cygni" title="SU Cygni">SU Cyg</a> </td> <td><a href="/wiki/Cygnus_(constellation)" title="Cygnus (constellation)">Cygnus</a> </td> <td>  </td> <td>6<sup>m</sup>.44 </td> <td>7<sup>m</sup>.22 </td> <td>03.84555 </td> <td>F2-G0I-II<sup id="cite_ref-andrievsky_47-0" class="reference"><a href="#cite_note-andrievsky-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> </td> <td>  </td></tr> <tr> <td><a href="/wiki/Beta_Doradus" title="Beta Doradus">β Dor</a> </td> <td><a href="/wiki/Dorado" title="Dorado">Dorado</a> </td> <td>  </td> <td>3<sup>m</sup>.46 </td> <td>4<sup>m</sup>.08 </td> <td>09.8426 </td> <td>F4-G4Ia-II </td> <td>  </td></tr> <tr> <td><a href="/wiki/Zeta_Geminorum" title="Zeta Geminorum">ζ Gem</a> </td> <td><a href="/wiki/Gemini_(constellation)" title="Gemini (constellation)">Gemini</a> </td> <td><a href="/wiki/Johann_Friedrich_Julius_Schmidt" title="Johann Friedrich Julius Schmidt">Julius Schmidt</a>, 1825 </td> <td>3<sup>m</sup>.62 </td> <td>4<sup>m</sup>.18 </td> <td>10.15073 </td> <td>F7Ib to G3Ib </td> <td>  </td></tr> <tr> <td><a href="/wiki/V473_Lyrae" title="V473 Lyrae">V473 Lyr</a> </td> <td><a href="/wiki/Lyra" title="Lyra">Lyra</a> </td> <td>  </td> <td>5<sup>m</sup>.99 </td> <td>6<sup>m</sup>.35 </td> <td>01.49078 </td> <td>F6Ib-II </td> <td>  </td></tr> <tr> <td><a href="/wiki/R_Muscae" title="R Muscae">R Mus</a> </td> <td><a href="/wiki/Musca" title="Musca">Musca</a> </td> <td>  </td> <td>5<sup>m</sup>.93 </td> <td>6<sup>m</sup>.73 </td> <td>07.51 </td> <td>F7Ib-G2 </td> <td>  </td></tr> <tr> <td><a href="/wiki/S_Muscae" title="S Muscae">S Mus</a> </td> <td><a href="/wiki/Musca" title="Musca">Musca</a> </td> <td>  </td> <td>5<sup>m</sup>.89 </td> <td>6<sup>m</sup>.49 </td> <td>09.66007 </td> <td>F6Ib-G0 </td> <td>  </td></tr> <tr> <td><a href="/wiki/S_Normae" title="S Normae">S Nor</a> </td> <td><a href="/wiki/Norma_(constellation)" title="Norma (constellation)">Norma</a> </td> <td>  </td> <td>6<sup>m</sup>.12 </td> <td>6<sup>m</sup>.77 </td> <td>09.75411 </td> <td>F8-G0Ib </td> <td>brightest member of open cluster <a href="/wiki/NGC_6087" title="NGC 6087">NGC 6087</a> </td></tr> <tr> <td><a href="/w/index.php?title=QZ_Normae&action=edit&redlink=1" class="new" title="QZ Normae (page does not exist)">QZ Nor</a> </td> <td><a href="/wiki/Norma_(constellation)" title="Norma (constellation)">Norma</a> </td> <td>  </td> <td>8<sup>m</sup>.71 </td> <td>9<sup>m</sup>.03 </td> <td>03.786008 </td> <td>F6I </td> <td>member of open cluster <a href="/wiki/NGC_6067" title="NGC 6067">NGC 6067</a> </td></tr> <tr> <td><a href="/w/index.php?title=V340_Normae&action=edit&redlink=1" class="new" title="V340 Normae (page does not exist)">V340 Nor</a> </td> <td><a href="/wiki/Norma_(constellation)" title="Norma (constellation)">Norma</a> </td> <td>  </td> <td>8<sup>m</sup>.26 </td> <td>8<sup>m</sup>.60 </td> <td>11.2888 </td> <td>G0Ib </td> <td>member of open cluster <a href="/wiki/NGC_6067" title="NGC 6067">NGC 6067</a> </td></tr> <tr> <td><a href="/wiki/V378_Normae" title="V378 Normae">V378 Nor</a> </td> <td><a href="/wiki/Norma_(constellation)" title="Norma (constellation)">Norma</a> </td> <td>  </td> <td>6<sup>m</sup>.21 </td> <td>6<sup>m</sup>.23 </td> <td>03.5850 </td> <td>G8Ib </td> <td>  </td></tr> <tr> <td><a href="/w/index.php?title=BF_Ophiuchi&action=edit&redlink=1" class="new" title="BF Ophiuchi (page does not exist)">BF Oph</a> </td> <td><a href="/wiki/Ophiuchus" title="Ophiuchus">Ophiuchus</a> </td> <td>  </td> <td>6<sup>m</sup>.93 </td> <td>7<sup>m</sup>.71 </td> <td>04.06775 </td> <td>F8-K2<sup id="cite_ref-densities_48-0" class="reference"><a href="#cite_note-densities-48"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup> </td> <td>  </td></tr> <tr> <td><a href="/wiki/RS_Puppis" title="RS Puppis">RS Pup</a> </td> <td><a href="/wiki/Puppis" title="Puppis">Puppis</a> </td> <td>  </td> <td>6<sup>m</sup>.52 </td> <td>7<sup>m</sup>.67 </td> <td>41.3876 </td> <td>F8Iab </td> <td>  </td></tr> <tr> <td><a href="/wiki/S_Sagittae" title="S Sagittae">S Sge</a> </td> <td><a href="/wiki/Sagitta" title="Sagitta">Sagitta</a> </td> <td><a href="/wiki/John_Ellard_Gore" title="John Ellard Gore">John Ellard Gore</a>, 1885 </td> <td>5<sup>m</sup>.24 </td> <td>6<sup>m</sup>.04 </td> <td>08.382086<sup id="cite_ref-AAVSOS_49-0" class="reference"><a href="#cite_note-AAVSOS-49"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup> </td> <td>F6Ib-G5Ib </td> <td>  </td></tr> <tr> <td><a href="/wiki/U_Sagittarii" title="U Sagittarii">U Sgr</a> </td> <td><a href="/wiki/Sagittarius_(constellation)" title="Sagittarius (constellation)">Sagittarius</a> (in <a href="/wiki/Messier_25" title="Messier 25">M25</a>) </td> <td>  </td> <td>6<sup>m</sup>.28 </td> <td>7<sup>m</sup>.15 </td> <td>06.74523 </td> <td>G1Ib<sup id="cite_ref-2d_50-0" class="reference"><a href="#cite_note-2d-50"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> </td> <td>  </td></tr> <tr> <td><a href="/wiki/W_Sagittarii" title="W Sagittarii">W Sgr</a> </td> <td><a href="/wiki/Sagittarius_(constellation)" title="Sagittarius (constellation)">Sagittarius</a> </td> <td>  </td> <td>4<sup>m</sup>.29 </td> <td>5<sup>m</sup>.14 </td> <td>07.59503 </td> <td>F4-G2Ib </td> <td>Optical double with <a href="/wiki/Gamma2_Sagittarii" title="Gamma2 Sagittarii">γ<sup>2</sup> Sgr</a> </td></tr> <tr> <td><a href="/wiki/X_Sagittarii" title="X Sagittarii">X Sgr</a> </td> <td><a href="/wiki/Sagittarius_(constellation)" title="Sagittarius (constellation)">Sagittarius</a> </td> <td>  </td> <td>4<sup>m</sup>.20 </td> <td>4<sup>m</sup>.90 </td> <td>07.01283 </td> <td>F5-G2II </td> <td> </td></tr> <tr> <td><a href="/wiki/V636_Scorpii" title="V636 Scorpii">V636 Sco</a> </td> <td><a href="/wiki/Scorpius" title="Scorpius">Scorpius</a> </td> <td>  </td> <td>6<sup>m</sup>.40 </td> <td>6<sup>m</sup>.92 </td> <td>06.79671 </td> <td>F7/8Ib/II-G5 </td> <td>  </td></tr> <tr> <td><a href="/wiki/R_Trianguli_Australis" title="R Trianguli Australis">R TrA</a> </td> <td><a href="/wiki/Triangulum_Australe" title="Triangulum Australe">Triangulum Australe</a> </td> <td>  </td> <td>6<sup>m</sup>.4 </td> <td>6<sup>m</sup>.9 </td> <td>03.389 </td> <td>F7Ib/II<sup id="cite_ref-2d_50-1" class="reference"><a href="#cite_note-2d-50"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> </td> <td>  </td></tr> <tr> <td><a href="/wiki/S_Trianguli_Australis" title="S Trianguli Australis">S TrA</a> </td> <td><a href="/wiki/Triangulum_Australe" title="Triangulum Australe">Triangulum Australe</a> </td> <td>  </td> <td>6<sup>m</sup>.1 </td> <td>6<sup>m</sup>.8 </td> <td>06.323 </td> <td>F6II-G2 </td> <td>  </td></tr> <tr> <td>α UMi (<a href="/wiki/Polaris" title="Polaris">Polaris</a>) </td> <td><a href="/wiki/Ursa_Minor" title="Ursa Minor">Ursa Minor</a> </td> <td><a href="/wiki/Ejnar_Hertzsprung" title="Ejnar Hertzsprung">Ejnar Hertzsprung</a>, 1911 </td> <td>1<sup>m</sup>.86 </td> <td>2<sup>m</sup>.13 </td> <td>03.9696 </td> <td>F8Ib or F8II </td> <td>  </td></tr> <tr> <td><a href="/wiki/AH_Velorum" title="AH Velorum">AH Vel</a> </td> <td><a href="/wiki/Vela_(constellation)" title="Vela (constellation)">Vela</a> </td> <td>  </td> <td>5<sup>m</sup>.5 </td> <td>5<sup>m</sup>.89 </td> <td>04.227171 </td> <td>F7Ib-II </td> <td>  </td></tr> <tr> <td><a href="/wiki/S_Vulpeculae" title="S Vulpeculae">S Vul</a> </td> <td><a href="/wiki/Vulpecula" title="Vulpecula">Vulpecula</a> </td> <td>  </td> <td>8<sup>m</sup>.69 </td> <td>9<sup>m</sup>.42 </td> <td>68.464 </td> <td>G0-K2(M1) </td> <td>  </td></tr> <tr> <td><a href="/wiki/T_Vulpeculae" title="T Vulpeculae">T Vul</a> </td> <td><a href="/wiki/Vulpecula" title="Vulpecula">Vulpecula</a> </td> <td>  </td> <td>5<sup>m</sup>.41 </td> <td>6<sup>m</sup>.09 </td> <td>04.435462 </td> <td>F5Ib-G0Ib </td> <td>  </td></tr> <tr> <td><a href="/wiki/U_Vulpeculae" title="U Vulpeculae">U Vul</a> </td> <td><a href="/wiki/Vulpecula" title="Vulpecula">Vulpecula</a> </td> <td>  </td> <td>6<sup>m</sup>.73 </td> <td>7<sup>m</sup>.54 </td> <td>07.990676 </td> <td>F6Iab-G2 </td> <td>  </td></tr> <tr> <td><a href="/wiki/SV_Vulpeculae" title="SV Vulpeculae">SV Vul</a> </td> <td><a href="/wiki/Vulpecula" title="Vulpecula">Vulpecula</a> </td> <td>  </td> <td>6<sup>m</sup>.72 </td> <td>7<sup>m</sup>.79 </td> <td>44.993 </td> <td>F7Iab-K0Iab </td> <td>  </td></tr> <tr> <td><a href="/w/index.php?title=SU_Cas&action=edit&redlink=1" class="new" title="SU Cas (page does not exist)">SU Cas</a> </td> <td><a href="/wiki/Cassiopeia_(constellation)" title="Cassiopeia (constellation)">Cassiopeia</a> </td> <td>  </td> <td>5<sup>m</sup>.88 </td> <td>6<sup>m</sup>.30 </td> <td>01.9 </td> <td>F5II </td> <td>  </td></tr></tbody></table> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Classical_Cepheid_variable&action=edit&section=8" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/RR_Lyrae_variable" title="RR Lyrae variable">RR Lyrae variable</a></li> <li><a href="/wiki/Stellar_pulsation" title="Stellar pulsation">Stellar pulsation</a></li> <li><a href="/wiki/Type_II_Cepheid" title="Type II Cepheid">Type II Cepheid</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Classical_Cepheid_variable&action=edit&section=9" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width reflist-columns-2"> <ol class="references"> <li id="cite_note-OGLE_4-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-OGLE_4_1-0">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output 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External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20101009205927/http://www.institute-of-brilliant-failures.com/">The Cepheid Distance Scale: A History, by Nick Allen</a></li> <li><a rel="nofollow" class="external text" href="https://crocus.physics.mcmaster.ca/Cepheid/Classical.html">List of classical Cepheids on McMaster Cepheid Photometry and Radial Velocity Data Archive</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20211008185122/https://crocus.physics.mcmaster.ca/Cepheid/Classical.html">Archived</a> 2021-10-08 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></li> <li><a rel="nofollow" class="external text" href="http://www.aavso.org/">American Association of Variable Star Observers</a></li> <li><a rel="nofollow" class="external text" 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star">Variable stars</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Stellar_pulsation" title="Stellar pulsation">Pulsating</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Cepheid_variable" title="Cepheid variable">Cepheids</a> and<br />cepheid-like</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Type_I_Cepheid" class="mw-redirect" title="Type I Cepheid">Type I</a> <small>(<a class="mw-selflink selflink">Classical cepheids</a>, <a href="/wiki/Delta_Scuti_variable" title="Delta Scuti variable">Delta Scuti</a>)</small></li> <li><a href="/wiki/Type_II_Cepheid" title="Type II Cepheid">Type II</a> <small>(<a href="/wiki/BL_Herculis_variable" title="BL Herculis variable">BL Herculis</a>, <a href="/wiki/W_Virginis_variable" title="W Virginis variable">W Virginis</a>, <a href="/wiki/RV_Tauri_variable" title="RV Tauri variable">RV Tauri</a>)</small></li> <li><a href="/wiki/RR_Lyrae_variable" title="RR Lyrae variable">RR Lyrae</a></li> <li><a href="/wiki/Rapidly_oscillating_Ap_star" title="Rapidly oscillating Ap star">Rapidly oscillating Ap</a></li> <li><a href="/wiki/SX_Phoenicis_variable" title="SX Phoenicis variable">SX Phoenicis</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Blue-white with<br />early spectra</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alpha_Cygni_variable" title="Alpha Cygni variable">Alpha Cygni</a></li> <li><a href="/wiki/Beta_Cephei_variable" title="Beta Cephei variable">Beta Cephei</a></li> <li><a href="/wiki/Slowly_pulsating_B-type_star" title="Slowly pulsating B-type star">Slowly pulsating B-type</a></li> <li><a href="/wiki/PV_Telescopii_variable" title="PV Telescopii variable">PV Telescopii</a></li> <li><a href="/wiki/Blue_large-amplitude_pulsator" title="Blue large-amplitude pulsator">Blue large-amplitude pulsator</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Long-period_variable_star" title="Long-period variable star">Long-period</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Mira_variable" title="Mira variable">Mira</a></li> <li><a href="/wiki/Semiregular_variable_star" title="Semiregular variable star">Semiregular</a></li> <li><a href="/wiki/Slow_irregular_variable" title="Slow irregular variable">Slow irregular</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Gamma_Doradus_variable" title="Gamma Doradus variable">Gamma Doradus</a></li> <li><a href="/wiki/Solar-like_oscillations" title="Solar-like oscillations">Solar-like oscillations</a></li> <li><a href="/wiki/Pulsating_white_dwarf" title="Pulsating white dwarf">White dwarf</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Eruptive</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Pre-main-sequence_star" title="Pre-main-sequence star">Protostar</a> and <a href="/wiki/Pre-main-sequence_star" title="Pre-main-sequence star">PMS</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Herbig_Ae/Be_star" title="Herbig Ae/Be star">Herbig Ae/Be</a></li> <li><a href="/wiki/Orion_variable" title="Orion variable">Orion</a> <ul><li><small><a href="/wiki/FU_Orionis_star" title="FU Orionis star">FU Orionis</a></small></li> <li><small><a href="/wiki/T_Tauri_star" title="T Tauri star">T Tauri</a></small></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Giants and<br />supergiants</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Luminous_blue_variable" title="Luminous blue variable">Luminous blue variable</a></li> <li><a href="/wiki/R_Coronae_Borealis_variable" title="R Coronae Borealis variable">R Coronae Borealis</a> <small>(<a href="/wiki/DY_Persei_variable" title="DY Persei variable">DY Persei</a>)</small></li> <li><a href="/wiki/Yellow_hypergiant" title="Yellow hypergiant">Yellow hypergiant</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Eruptive binary</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Double_periodic_variable" title="Double periodic variable">Double periodic</a></li> <li><a href="/wiki/FS_Canis_Majoris_variable" title="FS Canis Majoris variable">FS Canis Majoris</a></li> <li><a href="/wiki/RS_Canum_Venaticorum_variable" title="RS Canum Venaticorum variable">RS Canum Venaticorum</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Flare_star" title="Flare star">Flare</a></li> <li><a href="/wiki/Gamma_Cassiopeiae_variable" title="Gamma Cassiopeiae variable">Gamma Cassiopeiae</a></li> <li><a href="/wiki/Lambda_Eridani_variable" title="Lambda Eridani variable">Lambda Eridani</a></li> <li><a href="/wiki/Wolf%E2%80%93Rayet_star" title="Wolf–Rayet star">Wolf–Rayet</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Cataclysmic_variable_star" title="Cataclysmic variable star">Cataclysmic</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/AM_Canum_Venaticorum_star" title="AM Canum Venaticorum star">AM Canum Venaticorum</a></li> <li><a href="/wiki/Dwarf_nova" title="Dwarf nova">Dwarf nova</a></li> <li><a href="/wiki/Luminous_red_nova" title="Luminous red nova">Luminous red nova</a></li> <li><a href="/wiki/Nova" title="Nova">Nova</a></li> <li><a href="/wiki/Polar_(star)" title="Polar (star)">Polar</a> <ul><li><small><a href="/wiki/Intermediate_polar" title="Intermediate polar">Intermediate</a></small></li></ul></li> <li><a href="/wiki/Supernova" title="Supernova">Supernova</a> <ul><li><small><a href="/wiki/Hypernova" title="Hypernova">Hypernova</a></small></li></ul></li> <li><a href="/wiki/SW_Sextantis_variable" title="SW Sextantis variable">SW Sextantis</a></li> <li><a href="/wiki/Symbiotic_binary" title="Symbiotic binary">Symbiotic</a> <ul><li><small><a href="/wiki/Symbiotic_nova" title="Symbiotic nova">Symbiotic nova</a></small></li> <li><small><a href="/wiki/Symbiotic_binary" title="Symbiotic binary">Z Andromedae</a></small></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Rotating</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Non-spherical</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Rotating_ellipsoidal_variable" title="Rotating ellipsoidal variable">Rotating ellipsoidal</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Stellar spots</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/BY_Draconis_variable" title="BY Draconis variable">BY Draconis</a></li> <li><a href="/wiki/Variable_star#FK_Comae_Berenices_variables" title="Variable star">FK Comae Berenices</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Magnetic fields</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Alpha2_Canum_Venaticorum_variable" title="Alpha2 Canum Venaticorum variable">α<sup>2</sup> Canum Venaticorum</a></li> <li><a href="/wiki/Pulsar" title="Pulsar">Pulsar</a></li> <li><a href="/wiki/SX_Arietis_variable" title="SX Arietis variable">SX Arietis</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Binary_star#Eclipsing_binaries" title="Binary star">Eclipsing</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Algol_variable" title="Algol variable">Algol</a></li> <li><a href="/wiki/Beta_Lyrae_variable" title="Beta Lyrae variable">Beta Lyrae</a></li> <li><a href="/wiki/Planetary_transit_variable" class="mw-redirect" title="Planetary transit variable">Planetary transit</a></li> <li><a href="/wiki/W_Ursae_Majoris_variable" title="W Ursae Majoris variable">W Ursae Majoris</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" 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