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**金牛座EU**
觀測資料; 曆元 J2000.0
星座	金牛座
星官
赤經	05h 45m 40.529s
赤緯	18° 39′ 24.82″
視星等（V）	8.07 (7.90 to 8.25)
特性
光谱分类	G5
B−V 色指数	0.676+0.018; −
变星类型	s-Cepheid
天体测定
徑向速度 (Rv)	−2.5+0.3; − km/s
自行 (μ)	赤经：1.155 mas/yr ; 赤纬：−2.455 mas/yr
视差 (π)	0.8262 ± 0.0233 mas
距离	3,900 ± 100 ly ; (1,210 ± 30 pc)
绝对星等 (MV)	−2.77+0.15; −
詳細資料
質量	4.95+0.20; − M☉
半徑	30.23+1.43; − R☉
亮度	1,038+140; − L☉
溫度	6,404 (6,185 to 6,626) K
金属量 [Fe/H]	−0.06 dex
年齡	195 Myr
其他命名
	EU Tau、BD+18°955、HD 38321、HIP 27183、SAO 94837、PPM 121367
參考資料庫
SIMBAD	资料

金牛座EU是在黃道星座金牛座的一顆變星。平均的視星等的亮度為8.07等^[2]，它太微弱了，因此肉眼看不到。基於視差的測量，到這顆恆星的距離約為3,900光年^[1]，但它正在以-2.5公里/秒的徑向速度漂移^[5]。這顆恆星在黃道附近的位置意味著它會發生月掩星的事件^[10]。

這顆恆星的變異性最早是由庫諾·霍夫邁斯特（英语：Cuno Hoffmeister）在1949年報導的，但後來他又報告說它沒有變異。由佛蘭克·布拉德肖·伍德（英语：Frank Bradshaw Wood）和同事於1963年根據阿扎爾諾娃（T. A. Azarnova）在1950-1951年的觀察，它最初被歸類為大熊座W型變星。愛德華·吉南（英语：Edward Guinan）在1966年對光電數據的分析表明，這是一顆造父型變星，其短的脈動週期約為2.105天^[12]。他在1972年將這一時期精確為2.1051+0.0004
−天^[13]。

1981年對這個和其它造父變星的光變曲線的研究表明，它屬於一個具有異常短時間和獨特行為的小群體。這表明金牛座EU可能是「第一個泛音」脈動星^[14]。1987年，Gieren和傑米·馬修斯（英语：Jaymie M. Matthews）提出這顆恆星可能有兩個脈動週期，但後來被駁斥了。現在的證據主要支援恆星脈動處於「徑向第一泛音模式」的觀點。對於這類恆星來說，脈動週期中1%的半徑變化相對較小^[6]，到2007年，分散在35年時間範圍內的觀測表明，這顆造父變星的脈動週期可能已經改變^[15]。

參考資料

^ ^1.0 ^1.1 ^1.2 ^1.3 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 . doi:10.1051/0004-6361/202039657 . 已忽略未知参数|collaboration= (帮助) (勘误: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ ^2.0 ^2.1 ^2.2 Anderson, E.; Francis, Ch., XHIP: An extended hipparcos compilation, Astronomy Letters, 2012, 38 (5): 331, Bibcode:2012AstL...38..331A, S2CID 119257644, arXiv:1108.4971 , doi:10.1134/S1063773712050015.
^ ^3.0 ^3.1 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.
^ Cannon, A. J.; Pickering, E. C., Henry Draper Catalogue and Extension (Cannon+ 1918-1924; ADC 1989), VizieR Online Data Catalog, October 1, 1993, 3135, Bibcode:1993yCat.3135....0C.
^ ^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 , doi:10.1134/S1063773706110065.
^ ^6.0 ^6.1 ^6.2 ^6.3 ^6.4 Gieren, Wolfgang P.; et al, The Short-Period Cepheid EU Tau. II. Physical Properties of the Star, Astronomical Journal, April 1990, 99: 1196, Bibcode:1990AJ.....99.1196G, doi:10.1086/115408.
^ Bersier, D.; et al, Fundamental parameters of Cepheids. IV. Radii and luminosities, Astronomy and Astrophysics, April 1997, 320: 228–236, Bibcode:1997A&A...320..228B.
^ ^8.0 ^8.1 Marsakov, V. A.; et al, Properties of the population of classical Cepheids in the Galaxy, Astronomy Letters, 2013, 39 (12): 851, Bibcode:2013AstL...39..851M, S2CID 119788977, doi:10.1134/S1063773713120050.
^ EU Tau. SIMBAD. 斯特拉斯堡天文資料中心.
^ Evans, D. S.; Edwards, D. A., Photoelectric observations of lunar occultations. XII, Astronomical Journal, August 1981, 86: 1277−1287, Bibcode:1981AJ.....86.1277E, doi:10.1086/113008. In particular, the SAO 94837 entry on p. 1280.
^ MAST: Barbara A. Mikulski Archive for Space Telescopes. Space Telescope Science Institute. [8 December 2021]. （原始内容存档于2023-03-27）.
^ Guinan, E. F., EU Tauri, Information Bulletin on Variable Stars, December 1966, 170: 1, Bibcode:1966IBVS..170....1G.
^ Guinan, E. F., UBV beta photometry of EU Tau, Publications of the Astronomical Society of the Pacific, February 1972, 84: 56, Bibcode:1972PASP...84...56G, S2CID 120659500, doi:10.1086/129245.
^ Simon, N. R.; Lee, A. S., The structural properties of cepheid light curves, Astrophysical Journal, August 1981, 248: 291–297 [2023-08-22], Bibcode:1981ApJ...248..291S, doi:10.1086/159153, （原始内容存档于2023-08-02）.
^ Boyer, Kirk; et al, EU Tauri: An S-cepheid With A Changing Period, Bulletin of the American Astronomical Society, December 2007, 39: 845, Bibcode:2007AAS...211.6014B.

進階讀物

Matthews, J. M.; Gieren, W. P., Schmidt, E. G. , 编, Secular Changes in the Light Curve of the Short-Period Cepheid EU Tau, The Use of pulsating stars in fundamental problems of astronomy, Proceedings of IAU Colloq. 111, held in Lincoln, NE, 15–17 August 1988 (Cambridge University Press), 1989: 275, Bibcode:1989upsf.conf..275M.
Gieren, Wolfgang P.; et al, The Short-Period Cepheid EU Tau. I. New Photometric and Radial Velocity Data, Astronomical Journal, November 1989, 98: 1672, Bibcode:1989AJ.....98.1672G, doi:10.1086/115253.
Fernie, J. D., A check on EU Tauri, Publications of the Astronomical Society of the Pacific, October 1987, 99: 1093–1096, Bibcode:1987PASP...99.1093F, S2CID 120308156, doi:10.1086/132084.
Matthews, Jaymie M.; Gieren, Wolfgang P., Cox, A. N.; et al , 编, Frequency Analysis of the Unusual Short-Period Cepheid EU Tauri, Stellar Pulsation; Proceedings of the Conference held as a Memorial to John P. Cox at the Los Alamos National Laboratory, Los Alamos, NM, Aug. 11-15, 1986. Lecture Notes in Physics, Vol. 274, Lecture Notes in Physics 274 (Berlin: Springer-Verlag), 1987, 274: 187, Bibcode:1987LNP...274..187M, ISBN 978-3-540-17668-8, doi:10.1007/3-540-17668-3_202.
Gieren, W. P., Madore, B. F. , 编, A Study of the Short-period Cepheid EU-Tauri (PDF), Cepheids: Theory and Observations, Proceedings of IAU Colloquium No. 82, held 29 May - 1 June 1984 in Toronto, Canada (82) (New York: Cambridge University Press), June 1985, (82): 98 [2022-06-30], Bibcode:1985cto..conf...98G.
Sanwal, N. B.; Parthasarathy, M., UBV photometry of EU Tau., Astronomy and Astrophysics Supplement Series, January 1974, 13: 91–97, Bibcode:1974A&AS...13...91S.