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Alpha Cygni variable
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<h2 id="pulsations">Pulsations</h2> <p>The pulsations of Alpha Cygni Variable stars are not fully understood. They are not confined to a narrow range of temperatures and luminosities in the way that most pulsating stars are. Instead, most luminous A and B supergiants, and possibly also O and F stars, show some type of unpredictable small-scale pulsations. <a href="/facts/Adiabatic_process/rJj42U5h">Nonadiabatic</a> strange mode <a href="/facts/Radial_pulsations/vm2gJu6o">radial pulsations</a> are predicted but only for the most luminous supergiants. Pulsations have also been modelled for less luminous supergiants by assuming they are low mass post-red supergiant stars, but most Alpha Cygni variables do not appear to have passed through the red supergiant stage.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p><p>The pulsations are likely induced by <a href="/facts/Kappa_mechanism/DEXmpjvY">kappa mechanism</a>, caused by iron opacity variations, with strange modes producing the observed short periods for both radial and non-radial pulsations. Non-adiabatic <a href="/facts/G-mode_pulsation/HHazND81">g-modes</a> may produce longer period variations, but these have not been observed in Alpha Cygni variables.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p> <h2 id="list">List</h2> <h3>Galactic</h3> <table><tbody><tr><th>Designation (name)</th><th>Constellation</th><th>Discovery</th><th><i>Maximum <a href="/facts/Apparent_magnitude/7pCTF1Me">Apparent magnitude</a></i> (mV)<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></th><th><i>Minimum <a href="/facts/Apparent_magnitude/7pCTF1Me">Apparent magnitude</a></i> (mV)<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></th><th>Period (days)</th><th>Spectral class</th><th>Luminosity</th><th>Comment</th></tr><tr><td><a href="/facts/HD_21389/sabN6fP8">CE Cam (HD 21389)</a></td><td><a href="/facts/Camelopardalis/7RN3GScR">Camelopardalis</a></td><td>Percy & Welsh (1983)<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></td><td>4m.54</td><td></td><td></td><td>A0Iab</td><td>63,000<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a></td><td> </td></tr><tr><td><a href="/facts/CS_Camelopardalis/DQKoL9wq">CS Cam</a></td><td><a href="/facts/Camelopardalis/7RN3GScR">Camelopardalis</a></td><td>Rufener (1982)<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a></td><td>4m.259</td><td></td><td></td><td>B9Ia</td><td>75,900<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></td><td> </td></tr><tr><td><a href="/facts/Eta_Canis_Majoris/GxLt319S">η CMa (Aludra)</a></td><td><a href="/facts/Canis_Major/mqRyjJoM">Canis Major</a></td><td>Kazarovets et al. (1999)<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a></td><td>2m.38</td><td>2m.48</td><td>4.70433</td><td>B5Ia</td><td>105,000<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></td><td> </td></tr><tr><td><a href="/facts/Omicron2_Canis_Majoris/wyLReGb5">ο2 CMa</a></td><td><a href="/facts/Canis_Major/mqRyjJoM">Canis Major</a></td><td>Waelkens et al. (1998)<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a></td><td>2m.98</td><td>3m.04</td><td>24.44</td><td>B3Ia</td><td>219,000<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></td><td> </td></tr><tr><td><a href="/facts/Kappa_Cassiopeiae/s5N5ELNn">κ Cas</a></td><td><a href="/facts/Cassiopeia_(constellation)/1SvXVyPT">Cassiopeia</a></td><td>Percy & Welsh (1983)<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></td><td>4m.12</td><td>4m.21</td><td>2.64690</td><td>B1Ia</td><td>331,000<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a></td><td> </td></tr><tr><td><a href="/facts/6_Cassiopeiae/2wjBJfX3">6 Cas</a></td><td><a href="/facts/Cassiopeia_(constellation)/1SvXVyPT">Cassiopeia</a></td><td>Abt (1957)<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a></td><td>5m.34</td><td>5m.45</td><td>30</td><td>B2 Ia+</td><td>200,000<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a></td><td>Hypergiant</td></tr><tr><td><a href="/facts/Omicron2_Centauri/qgV7aTCM">ο2 Cen</a></td><td><a href="/facts/Centaurus/NQEDC6xA">Centaurus</a></td><td></td><td>5m.12</td><td>5m.22</td><td>46.3</td><td>A2Ia</td><td>136,000<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a></td><td> </td></tr><tr><td><a href="/facts/Nu_Cephei/7UJmbrM1">ν Cep</a></td><td><a href="/facts/Cepheus_(constellation)/tlzYj8lT">Cepheus</a></td><td>Percy & Welsh (1983)<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a></td><td>4m.25</td><td>4m.35</td><td></td><td>A2 Iab</td><td>254,000<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a></td><td> </td></tr><tr><td><a href="/facts/DL_Crucis/TCUVyWCT">DL Cru</a></td><td><a href="/facts/Crux/Btht6rAc">Crux</a></td><td>Waelkens et al. (1998)<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a></td><td>6m.24</td><td>6m.28</td><td>2.8778</td><td>B1.5Ia</td><td>242,000<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a></td><td> </td></tr><tr><td><a href="/facts/Deneb/L7dTfcog">Deneb</a><a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a></td><td><a href="/facts/Cygnus_(constellation)/L1fYe414">Cygnus</a></td><td>Lee (1910)<a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a></td><td>1m.21</td><td>1m.29</td><td></td><td>A2 Ia</td><td>196,000<a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a></td><td>Prototype</td></tr><tr><td><a href="/facts/Sigma_Cygni/4wgvmtWe">σ Cyg</a></td><td><a href="/facts/Cygnus_(constellation)/L1fYe414">Cygnus</a></td><td>Abt (1957)<a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a></td><td>4m.19</td><td>4m.26</td><td>120.2</td><td>B9 Iab</td><td>39,000<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a></td><td> </td></tr><tr><td><a href="/facts/55_Cygni/TQ42rPrH">55 Cyg</a></td><td><a href="/facts/Cygnus_(constellation)/L1fYe414">Cygnus</a></td><td>Hill et al. (1976)<a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a></td><td>4m.81</td><td>4m.87</td><td></td><td>B2.5 Ia</td><td>~400,000<a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a></td><td> </td></tr><tr><td><a href="/facts/3_Geminorum/CavQqsEu">3 Gem</a></td><td><a href="/facts/Gemini_(constellation)/uTHx4pw9">Gemini</a></td><td>Waelkens et al. (1998)<a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a></td><td>5m.75</td><td></td><td>13.70</td><td>B3 Ia</td><td>200,000<a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a></td><td> </td></tr><tr><td><a href="/facts/Rho_Leonis/AwkeWw9E">ρ Leo</a></td><td><a href="/facts/Leo_(constellation)/B4knjuxd">Leo</a></td><td>Olsen (1974)<a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a></td><td>3m.83</td><td>3m.9</td><td>3.4271</td><td>B1Iab</td><td>295,000<a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a></td><td> </td></tr><tr><td><a href="/facts/Rigel/WeeIXAAv">β Ori (Rigel)</a><a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a></td><td><a href="/facts/Orion_(constellation)/bPeA8QYg">Orion</a></td><td>Waelkens et al. (1998)<a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a></td><td>0m.17</td><td>0m.22</td><td></td><td>B8Ia</td><td>279,000<a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a><p>218,000<a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a></p></td><td>Brightest member</td></tr><tr><td><a href="/facts/Alnilam/fM0f0CpF">ε Ori (Alnilam)</a></td><td><a href="/facts/Orion_(constellation)/bPeA8QYg">Orion</a></td><td>Cousins (1960)<a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a></td><td>1m.64</td><td>1m.74</td><td></td><td>B0.5Iabea</td><td>275,000<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a><p>537,000<a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a></p></td><td> </td></tr><tr><td><a href="/facts/Chi2_Orionis/cPfoWRmW">χ2 Ori</a></td><td><a href="/facts/Orion_(constellation)/bPeA8QYg">Orion</a></td><td>Waelkens et al. (1998)<a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a></td><td>4m.68</td><td>4m.72</td><td>2.8682</td><td>B2Ia</td><td>446,000<a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a></td><td> </td></tr><tr><td><a href="/facts/9_Persei/hcSuaebF">9 Per</a></td><td><a href="/facts/Perseus_(constellation)/KD8mcCCy">Perseus</a></td><td>Abt (1957)<a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a></td><td>5m.15</td><td>5m.25</td><td></td><td>A2 Ia</td><td>141,000<a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a></td><td> </td></tr></tbody></table> <h3>Extragalactic</h3> <table><tbody><tr><th>Designation (name)</th><th>Galaxy</th><th>Discovery</th><th><i>Maximum <a href="/facts/Apparent_magnitude/7pCTF1Me">Apparent magnitude</a></i> (mV)</th><th><i>Minimum <a href="/facts/Apparent_magnitude/7pCTF1Me">Apparent magnitude</a></i> (mV)</th><th>Period (days)</th><th>Spectral class</th><th>Luminosity</th><th>Comment</th></tr><tr><td>LHA 115-S 18<a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a></td><td><a href="/facts/Small_Magellanic_Cloud/jg9s2YCl">SMC</a></td><td></td><td>13m.3</td><td></td><td>Complex</td><td>B[e]sg</td><td> </td><td>Possible LBV</td></tr><tr><td><a href="/facts/HDE_268835/eLvuuTg5">HDE 268835</a><a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a></td><td><a href="/facts/Large_Magellanic_Cloud/7VYAehNa">LMC</a></td><td></td><td>10m.60</td><td>10m.68</td><td>>100</td><td>B8p</td><td> </td><td> </td></tr><tr><td><a href="/facts/HD_37974/NxyPJ66m">HD 37974</a><a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a></td><td><a href="/facts/Large_Magellanic_Cloud/7VYAehNa">LMC</a></td><td></td><td>10m.92</td><td>11m.00</td><td>400</td><td>B0.5Ia+</td><td> </td><td> </td></tr><tr><td><a href="/facts/HD_37836/NPLcKtlt">HD 37836</a><a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a></td><td><a href="/facts/Large_Magellanic_Cloud/7VYAehNa">LMC</a></td><td></td><td>10m.55</td><td></td><td></td><td>B0Iae</td><td></td><td>LBV candidate</td></tr></tbody></table> <h2 id="sources">Sources</h2> <ul><li>Samus N.N., Durlevich O.V., et al. <i>Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.)</i></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Kholopov, P. N.; Samus', N. N.; Frolov, M. S.; Goranskij, V. P.; Gorynya, N. A.; Kireeva, N. N.; Kukarkina, N. P.; Kurochkin, N. E.; Medvedeva, G. I.; Perova, N. B. (1996). "VizieR Online Data Catalog: General Catalog of Variable Stars, 4th Ed. (GCVS4) (Kholopov+ 1988)". VizieR On-Line Data Catalog: II/139B. Originally Published in: Moscow: Nauka Publishing House (1985–1988). 2139: 0. Bibcode:1996yCat.2139....0K. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Waelkens, C.; Aerts, C.; Kestens, E.; Grenon, M.; Eyer, L. (1998). "Study of an unbiased sample of B stars observed with Hipparcos: the discovery of a large amount of new slowly pulsating B star". Astronomy and Astrophysics. 330: 215–21. Bibcode:1998A&A...330..215W. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Saio, H.; Georgy, C.; Meynet, G. (2013). "Strange-Mode Instability for Micro-Variations in Luminous Blue Variables". Progress in Physics of the Sun and Stars: A New Era in Helio- and Asteroseismology. Proceedings of a Fujihara Seminar held 25–29 November. Astronomical Society of the Pacific Conference Series. Vol. 479. p. 47. arXiv:1305.4728. Bibcode:2013ASPC..479...47S. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Saio, H.; Georgy, C.; Meynet, G. (2013). "Evolution of blue supergiants and Cygni variables: puzzling CNO surface abundances". Monthly Notices of the Royal Astronomical Society. 433 (2): 1246–1257. arXiv:1305.2474. Bibcode:2013MNRAS.433.1246S. doi:10.1093/mnras/stt796. <a href="https://doi.org/10.1093%2Fmnras%2Fstt796" target="_blank">https://doi.org/10.1093%2Fmnras%2Fstt796</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Saio, Hideyuki (2011). "Linear analyses for the stability of radial and non-radial oscillations of massive stars". Monthly Notices of the Royal Astronomical Society. 412 (3): 1814–1822. arXiv:1011.4729. Bibcode:2011MNRAS.412.1814S. doi:10.1111/j.1365-2966.2010.18019.x. ISSN 0035-8711. S2CID 118552910. <a href="https://doi.org/10.1111%2Fj.1365-2966.2010.18019.x" target="_blank">https://doi.org/10.1111%2Fj.1365-2966.2010.18019.x</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-Line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: 02025. Bibcode:2009yCat....102025S. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-Line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: 02025. Bibcode:2009yCat....102025S. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Percy, J. R.; Welch, D. L. (1983). "Photometric variability of B- and A-type supergiants". Publications of the Astronomical Society of the Pacific. 95: 491. Bibcode:1983PASP...95..491P. doi:10.1086/131198. ISSN 0004-6280. <a href="https://doi.org/10.1086%2F131198" target="_blank">https://doi.org/10.1086%2F131198</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355, S2CID 111387483 <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Rufener, F.; Bartholdi, P. (1982). "List of 333 variable, microvariable or suspected variable stars detected in the Geneva photometry". Astronomy and Astrophysics Supplement Series. 48: 503. Bibcode:1982A&AS...48..503R. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>McErlean, N. D.; Lennon, D. J.; Dufton, P. L. (1999). "Galactic B-supergiants: A non-LTE model atmosphere analysis to estimate atmospheric parameters and chemical compositions". Astronomy and Astrophysics. 349: 553. Bibcode:1999A&A...349..553M. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V.; Frolov, M. S.; Antipin, S. V.; Kireeva, N. N.; Pastukhova, E. N. (1999). "The 74th Special Name-list of Variable Stars". Information Bulletin on Variable Stars. 4659: 1. Bibcode:1999IBVS.4659....1K. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355, S2CID 111387483 <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Waelkens, C.; Aerts, C.; Kestens, E.; Grenon, M.; Eyer, L. (1998). "Study of an unbiased sample of B stars observed with Hipparcos: the discovery of a large amount of new slowly pulsating B star". Astronomy and Astrophysics. 330: 215–21. Bibcode:1998A&A...330..215W. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Crowther, P. A.; Lennon, D. J.; Walborn, N. R. (2006). "Physical parameters and wind properties of galactic early B supergiants". Astronomy and Astrophysics. 446 (1): 279–293. arXiv:astro-ph/0509436. Bibcode:2006A&A...446..279C. doi:10.1051/0004-6361:20053685. S2CID 18815761. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Percy, J. R.; Welch, D. L. (1983). "Photometric variability of B- and A-type supergiants". Publications of the Astronomical Society of the Pacific. 95: 491. Bibcode:1983PASP...95..491P. doi:10.1086/131198. 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