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天鵝座X

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天鵝座X

根據「TESS」數據繪製的天鵝座X的光變曲線 [1]
觀測資料
曆元 J2000
星座 天鵝座
星官
赤經 20h 43m 24.192s[2]
赤緯 35° 35′ 16.08″[2]
視星等(V) 5.85 to 6.91[3]
特性
光譜分類F7 Ib to G8 Ib[4]
變星類型仙王座δ[3]
天體測定
徑向速度 (Rv)8.1+0.2
[5] km/s
自行 (μ) 赤經:−6.673 mas/yr
赤緯:−5.108 mas/yr
視差 (π)0.8842 ± 0.0199[2] mas
距離3,690 ± 80 ly
(1,130 ± 30 pc)
絕對星等 (MV)−4.53[6]
詳細資料
質量7.9–8.9[7] M
半徑95.9+1.6
[8] R
表面重力 (log g)1.601[9]
亮度5,202[10] L
溫度5,315+80
[8] K
金屬量 [Fe/H]0.10+0.08
[8] dex
自轉速度 (v sin i)8[7] km/s
年齡31[6] Myr
其他命名
X Cyg、​BD+35°4234、​GC 28886、​HD 197572、​HIP 102276、​HR 7932、​SAO 70423[11]
參考資料庫
SIMBAD資料

天鵝座X是在星座天鵝座北部的一顆變星,英文縮寫為X Cyg。這是一顆仙王座δ型變星,其視星等的亮度範圍從5.85到6.91的,週期為16.386332天[3]。在最亮的時候,這顆恆星肉眼隱約可見。根據視差的量測,到這顆恆星的距離約為628光年[2]。它正以8.1km/s的徑向速度遠離我們[5]。這顆恆星很可能是疏散星團魯普雷希特173英語Ruprecht 173的成員[12]

這顆恆星的變星光度是由小賽斯·卡羅·錢德勒於1886年發現的[13]。在1907年,埃德溫·布蘭特·弗羅斯特英語Edwin Brant Frost表明,天鵝座X是一顆F型恆星,具有不同的徑向速度,其行為類似於仙王座δ變星[14]米歇爾·路易澤英語Michel Luizet在1912年發現,這種變化的週期為16.38543天[15]。在1919年,弗蘭克·克雷格·喬丹英語Frank Craig Jordan確定恆星的色指數在每個週期中都會發生變化,隨著恆星變暗而變紅[16]。它被確定為滿足簡單周光關係的基準恆星類別經典造父變星的成員[17]

在1954年,羅伯特·克拉夫特在峰值亮度下發現其恆星分類為F7-Ib[18],與F型超巨星光譜相匹配。這顆恆星的光譜類型在脈動週期中變化,在最小亮度下低至G8 Ib[4]。在1956年,克拉夫特發現某些譜線加倍,他解釋說這是由於之前的脈動週期中,物質殼下落與光球碰撞的結果[19]。與大多數造父變星在每個週期經歷一次衝擊不同,天鵝座X被發現經歷了一次雙重衝擊[20]

現時還沒有發現軌道週期在十年或更短的伴星[21]。這顆恆星顯示出卷雲,並初步證明了紅外的長期發射[22]

參考資料

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  1. ^ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, [30 December 2022], (原始內容存檔於2023-03-27). 
  2. ^ 2.0 2.1 2.2 2.3 Brown, A. G. A.; et al. Gaia Early Data Release 3: Summary of the contents and survey properties. Astronomy & Astrophysics. 2021, 649: A1. Bibcode:2021A&A...649A...1G. S2CID 227254300. arXiv:2012.01533可免費查閱. doi:10.1051/0004-6361/202039657可免費查閱.  已忽略未知參數|collaboration= (幫助) (勘誤: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  3. ^ 3.0 3.1 3.2 Samus, N. N.; et al, General Catalogue of Variable Stars, Astronomy Reports, 5.1, 2017, 61 (1): 80–88, Bibcode:2017ARep...61...80S, S2CID 125853869, doi:10.1134/S1063772917010085. 
  4. ^ 4.0 4.1 Kovtyukh, V. V.; et al, Phase-dependent Variation of the Fundamental Parameters of Cepheids. II. Periods Longer than 10 Days, The Astronomical Journal, January 2005, 129 (1): 433–453, Bibcode:2005AJ....129..433K, S2CID 120666782, doi:10.1086/426339可免費查閱. 
  5. ^ 5.0 5.1 Gontcharov, G. A., Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system, Astronomy Letters, November 2006, 32 (11): 759–771, Bibcode:2006AstL...32..759G, S2CID 119231169, arXiv:1606.08053可免費查閱, doi:10.1134/S1063773706110065. 
  6. ^ 6.0 6.1 Acharova, I. A.; et al, Galactic restrictions on iron production by various types of supernovae, Monthly Notices of the Royal Astronomical Society, 2012, 420 (2): 1590, Bibcode:2012MNRAS.420.1590A, S2CID 118404944, arXiv:1111.2152可免費查閱, doi:10.1111/j.1365-2966.2011.20161.x. 
  7. ^ 7.0 7.1 Breitfellner, M. G.; Gillet, D., Atmospheric motions in classical cepheid stars. III. A very large amplitude star : X Cygni, Astronomy and Astrophysics, October 1993, 277: 553, Bibcode:1993A&A...277..553B. 
  8. ^ 8.0 8.1 8.2 Trahin, B.; et al, Inspecting the Cepheid parallax of pulsation using Gaia EDR3 parallaxes. Projection factor and period-luminosity and period-radius relations, Astronomy & Astrophysics, December 2021, 656, Bibcode:2021A&A...656A.102T, S2CID 244173657, arXiv:2111.09125可免費查閱, doi:10.1051/0004-6361/202141680, A102. 
  9. ^ Sprague, Dani; et al, APOGEE Net: An Expanded Spectral Model of Both Low-mass and High-mass Stars, The Astronomical Journal, March 8, 2022, 163 (4): 152, Bibcode:2022AJ....163..152S, ISSN 0004-6256, arXiv:2201.03661可免費查閱, doi:10.3847/1538-3881/ac4de7可免費查閱, eISSN 1538-3881. 
  10. ^ Groenewegen, M. A. T., The flux-weighted gravity-luminosity relation of Galactic classical Cepheids, Astronomy and Astrophysics, 2020, 640: A113, Bibcode:2020A&A...640A.113G, S2CID 220364506, arXiv:2007.02148可免費查閱, doi:10.1051/0004-6361/202038292. 
  11. ^ X Cyg. SIMBAD. 斯特拉斯堡天文資料中心. 
  12. ^ Anderson, Richard I.; et al, Cepheids in open clusters: an 8D all-sky census, Monthly Notices of the Royal Astronomical Society, September 2013, 434 (3): 2238–2261, Bibcode:2013MNRAS.434.2238A, arXiv:1212.5119可免費查閱, doi:10.1093/mnras/stt1160. 
  13. ^ Chandler, S. C., On a new short-period variable in Cygnus, Astronomical Journal, December 1886, 7 (148): 32, Bibcode:1886AJ......7...32C, doi:10.1086/100855. 
  14. ^ Frost, E. B., Nine stars having variable radial velocities, Astrophysical Journal, 1907, 25: 59–65, Bibcode:1907ApJ....25R..59F, doi:10.1086/141465. 
  15. ^ Luizet, Michel, Nouveaux éléments et courbes de lumière des étoiles X Cygni et RU Camelopardalis, Astronomische Nachrichten, November 1912, 193 (6): 83, Bibcode:1912AN....193...83L, doi:10.1002/asna.19121930603 (法語). 
  16. ^ Jordan, F. C., The color changes of certain variable stars of short period, Astrophysical Journal, October 1919, 50: 174–205, Bibcode:1919ApJ....50..174J, doi:10.1086/142495, hdl:2027/mdp.39015086631564可免費查閱. 
  17. ^ Eggen, Olin J., Photoelectric Studies. V. Magnitudes and Colors of Classical Cepheid Variable Stars, Astrophysical Journal, March 1951, 113: 367, Bibcode:1951ApJ...113..367E, doi:10.1086/145405可免費查閱. 
  18. ^ Kraft, Robert P., Changes in the Spectrum of X Cygni, Publications of the Astronomical Society of the Pacific, June 1954, 66 (390): 136, Bibcode:1954PASP...66..136K, S2CID 123620740, doi:10.1086/126679. 
  19. ^ Kraft, Robert P., Double Lines in the Spectrum of the Classical Cepheid X Cygni, Publications of the Astronomical Society of the Pacific, April 1956, 68 (401): 137, Bibcode:1956PASP...68..137K, S2CID 122849355, doi:10.1086/126897可免費查閱. 
  20. ^ Gillet, D., Atmospheric dynamics in long-period Cepheids. Hα profile variations, Astronomy & Astrophysics, August 2014, 568, Bibcode:2014A&A...568A..72G, doi:10.1051/0004-6361/201423486可免費查閱, A72. 
  21. ^ Hintz, Eric G.; et al, An Examination of Pulsational Changes in the Classical Cepheid X Cygni, The Astronomical Journal, October 2021, 162 (4): 149, Bibcode:2021AJ....162..149H, S2CID 237553133, doi:10.3847/1538-3881/ac167f可免費查閱, 149. 
  22. ^ Barmby, P.; et al, Galactic Cepheids with Spitzer. II. Search for Extended Infrared Emission, The Astronomical Journal, February 2011, 141 (2): 42, Bibcode:2011AJ....141...42B, S2CID 118581168, arXiv:1011.3386可免費查閱, doi:10.1088/0004-6256/141/2/42, 42. 

進階讀物

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