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金牛座EU

金牛座EU是在黄道星座金牛座的一颗变星。平均的视星等的亮度为8.07等[2]，它太微弱了，因此肉眼看不到。基于视差的测量，到这颗恒星的距离约为3,900光年[1]，但它正在以-2.5公里/秒的径向速度漂移[5]。这颗恒星在黄道附近的位置意味着它会发生月掩星的事件[10]。

金牛座EU
观测资料
历元 J2000.0
星座 金牛座
星官
赤经 05h 45m 40.529s[1]
赤纬 18° 39′ 24.82″[1]
视星等（V） 8.07[2] (7.90 to 8.25)[3]
特性
光谱分类G5[4]
B−V 色指数0.676+0.018
−[2]
变星类型s-Cepheid[3]
天体测定
径向速度 (Rv)−2.5+0.3
−[5] km/s
自行 (μ) 赤经：1.155 mas/yr
赤纬：−2.455 mas/yr
视差 (π)0.8262 ± 0.0233[1] mas
距离3,900 ± 100 ly
(1,210 ± 30 pc)
绝对星等 (MV)−2.77+0.15
−[6]
详细资料
质量4.95+0.20
−[6] M☉
半径30.23+1.43
−[6] R☉
亮度1,038+140
−[6] L☉
温度6,404 (6,185 to 6,626)[7] K
金属量 [Fe/H]−0.06[8] dex
年龄195[8] Myr
其他命名
EU Tau、​BD+18°955、​HD 38321、​HIP 27183、​SAO 94837、​PPM 121367[9]
参考数据库
SIMBAD资料
绘制自“TESS”
数据的金牛座EU 光变曲线[11]。

这颗恒星的变异性最早是由库诺·霍夫迈斯特（英语：Cuno Hoffmeister）在1949年报导的，但后来他又报告说它没有变异。由佛兰克·布拉德肖·伍德（英语：Frank Bradshaw Wood）和同事于1963年根据阿扎尔诺娃（T. A. Azarnova）在1950-1951年的观察，它最初被归类为大熊座W型变星。爱德华·吉南（英语：Edward Guinan）在1966年对光电数据的分析表明，这是一颗造父型变星，其短的脉动周期约为2.105天[12]。他在1972年将这一时期精确为2.1051+0.0004
−天[13]。

1981年对这个和其它造父变星的光变曲线的研究表明，它属于一个具有异常短时间和独特行为的小群体。这表明金牛座EU可能是“第一个泛音”脉动星[14]。1987年，Gieren和杰米·马修斯（英语：Jaymie M. Matthews）提出这颗恒星可能有两个脉动周期，但后来被驳斥了。 现在的证据主要支援恒星脉动处于“径向第一泛音模式”的观点。对于这类恒星来说，脉动周期中1%的半径变化相对较小[6]， 到2007年，分散在35年时间范围内的观测表明，这颗造父变星的脉动周期可能已经改变[15]。

参考资料

  1. ^ 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. ^ 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. ^ 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. 
  4. ^ 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. ^ 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. ^ 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. 
  7. ^ 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. ^ 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. 
  9. ^ EU Tau. SIMBAD. 斯特拉斯堡天文资料中心. 
  10. ^ 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.
  11. ^ 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）. 
  12. ^ Guinan, E. F., EU Tauri, Information Bulletin on Variable Stars, December 1966, 170: 1, Bibcode:1966IBVS..170....1G. 
  13. ^ 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. 
  14. ^ 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）. 
  15. ^ 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. 

进阶读物

  • 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. 
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