天鵝座X
| 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 | |
| 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型超巨星的光譜相匹配。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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. doi:10.1051/0004-6361/202039657 . 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. - ^ 3.0 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.
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- ^ 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 , doi:10.1111/j.1365-2966.2011.20161.x.
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- ^ 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 , doi:10.1051/0004-6361/202141680, A102.
- ^ 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 , doi:10.3847/1538-3881/ac4de7 , eISSN 1538-3881.
- ^ 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 , doi:10.1051/0004-6361/202038292.
- ^ X Cyg. SIMBAD. 斯特拉斯堡天文資料中心.
- ^ 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 , doi:10.1093/mnras/stt1160.
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- ^ 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 , A72.
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進階讀物
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- Meyer, Ralf, X Cyg: observations from 1886 until today, Open European Journal on Variable Stars, December 2005, 13: 1, Bibcode:2005OEJV...13....1M.
- Turner, David G., A Search for Stars Physically Associated with the 16 Day Cepheid X Cygni. II. Clusters in the Field, The Astronomical Journal, July 1998, 116 (1): 274–283, Bibcode:1998AJ....116..274T, S2CID 123331380, doi:10.1086/300438 .
- Wallerstein, G.; et al, A search for evidence of the neon-sodium cycle in the Cepheid X Cygni, Publications of the Astronomical Society of the Pacific, August 1984, 96: 613–617, Bibcode:1984PASP...96..613W, S2CID 120641485, doi:10.1086/131392.
- Evans, N. R., X Cygni: duplicity, period stability and atmospheric velocity structure, Astrophysical Journal, June 1984, 281: 760–765, Bibcode:1984ApJ...281..760E, doi:10.1086/162154 .
- Wallerstein, G., The behavior of H alpha in the 16-day cepheid X Cygni, Publications of the Astronomical Society of the Pacific, July 1983, 95: 422–426, Bibcode:1983PASP...95..422W, S2CID 122893194, doi:10.1086/131187 .
- Turner, D. G., A search for stars physically associated with the 16-day Cepheid X Cygni. I. Luminous Stars in the field, Astronomical Journal, May 1983, 88: 650–654, Bibcode:1983AJ.....88..650T, doi:10.1086/113353.
- Benz, W.; Mayor, M., Turbulence variations for the three cepheids SV Vul, X CYG and del Cep, Astronomy and Astrophysics, July 1982, 111: 224–228, Bibcode:1982A&A...111..224B.
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- Abt, H. A., Radial velocities of the cepheid X Cygni, Publications of the Astronomical Society of the Pacific, June 1978, 90: 309–311, Bibcode:1978PASP...90..309A, S2CID 120199788, doi:10.1086/130332 .
- Masani, A.; et al, The Masses of BM Cas, X Cyg, RT Aur, RR Lyr, Information Bulletin on Variable Stars, February 1968, 258: 1, Bibcode:1968IBVS..258....1M.
- Masani, A.; et al, Determination of the Mass and the Model of the Variables: RT Aurigae, Eta Aquilae, X Cygni, Mira Ceti and BM Cassiopeiae of Pop.I, and RR Lyrae and Two Typical Variables of Pop. II, Information Bulletin on Variable Stars, October 1966, 162: 1, Bibcode:1966IBVS..162....1M.
- Duncan, J. C., The spectroscopic orbit of the cepheid variable X Cygni, Astrophysical Journal, January 1921, 53: 95–98, Bibcode:1921ApJ....53...95D, doi:10.1086/142585.