金牛座EQ

金牛座EQ是黄道星座金牛座的一颗三合星，它包括密接的食双星。该系统过于黯淡，无法用肉眼观察，基线的视星等为10.5等^[3]。在食的期间，系统的主极小期亮度降至11.03等，然后在次极小期降至10.97等^[3]。次极小期是全食^[7]。根据视差的量测，它位于距离太阳约730光年的地方^[2]。

金牛座EQ

打印自“ASAS-SN”数据的金牛 座EQ在可见光波段的光变曲线[1]
观测资料 历元 J2000.0
星座	金牛座
星官
赤经	03h 48m 13.436s[2]
赤纬	+22° 18′ 50.92″[2]
视星等（V）	10.5 (-11.03)[3]
特性
光谱分类	G2[4]
变星类型	W UMa[3]
天体测定
径向速度 (Rv)	71.95+1.22 −[5] km/s
自行 (μ)	赤经：+69.758 mas/yr 赤纬：−30.628 mas/yr
视差 (π)	4.4694 ± 0.0171[2] mas
距离	730 ± 3 ly (223.7 ± 0.9 pc)
轨道[6]
绕行周期 (P)	0.341348 d
半长轴 (a)	7000248000000000000♠2.48±0.03 R☉[7]
偏心率 (e)	0.00
近心点 历元 (T)	7006245118390000000♠2,451,183.9 HJD
半振幅 (K1) (primary)	112.41+1.43 − km/s
半振幅 (K2) (secondary)	254.38+2.42 − km/s
详细资料
Primary
质量	1.22+0.04 −[7] M☉
半径	1.14+0.01 −[7] R☉
亮度	1.32+0.03 −[7] L☉
温度	5,800+100 −[7] K
Secondary
质量	0.54+0.02 −[7] M☉
半径	0.79+0.01 −[7] R☉
亮度	0.63+0.02 −[7] L☉
其他命名
EQ Tau、​GSC 01260-00909、​2MASS J03481342+2218509, HV 6189[8]
参考数据库
SIMBAD	资料

恒星HV 6189在1940年被哈罗·沙普利（ Harlow Shapley）和艾米莉·M·休斯（英语：Emily M. Hughes）（ Emily M. Hughes）确认为短周期变星^[9]，然后再1954年，苏联天文学家弗拉基米尔·普拉托诺维奇·采谢维奇（英语：Vladimir Platonovich Tsesevich）对其进行了更深入的研究^[6]。它被确定为大熊座W型变星，并被注意到位于疏散星团昴宿星团的区域^[10]。对采谢维奇数据的分析以及B.S.Whitney（英语：Balfour S.Whitney）在1972年的后续观测表明，它的周期是可变的。他在孔科利天文台（英语：Konkoly Observatory）的观测显示周期为8.19 h^[11]。Wystan Benbow（英语：Wystan Benbow）和Robert L.Mutel（英语：Robert L.Mutel）在1995年建立了食变星的光变曲线，显示了恒星表面存在活动区的证据^[12]。轨道周期的变化继续被观察到，在2002年Theodor Pribulla（英语：Theodor Pribulla）和Martin Vańko（英语：Martin Vańko）提出它是由系统中的第三个天体引起的。他们将其建模为低质量的红矮星，轨道周期为50.2年^[13]。

这是一个浅接触的联星系统^[7]，属于大熊座W型变星的A子型^[3]。它的轨道周期为8.1924小时^[6]，半长轴是太阳半径的2.48倍。轨道呈现周期性变化，其周期为22.7年，振幅为0.0058天。2010年观测到类似凌的事件^[7]。质量更大的成分是一颗有很深对流层的太阳型恒星，出现磁活动，覆盖着显著的星斑 ^[4]。

参考资料

1. ASAS-SN Variable Stars Database. ASAS-SN Variable Stars Database. ASAS-SN. [6 January 2022]. （原始内容存档于2023-01-11）.
2. 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.
3. Samus', N. N; et al, General catalogue of variable stars, Astronomy Reports, GCVS 5.1, 2017, 61 (1): 80, Bibcode:2017ARep...61...80S, S2CID 125853869, doi:10.1134/S1063772917010085.
4. Yuan, Jinzhao; Qian, Shengbang, Variation of the period and light curves of the solar-type contact binary EQ Tauri, Monthly Notices of the Royal Astronomical Society, October 2007, 381 (2): 602–610, Bibcode:2007MNRAS.381..602Y, doi:10.1111/j.1365-2966.2007.11926.x .
5. Bilir, S.; et al, Kinematics of W Ursae Majoris type binaries and evidence of the two types of formation, Monthly Notices of the Royal Astronomical Society, 2005, 357 (2): 497–517, Bibcode:2005MNRAS.357..497B, S2CID 16274339, arXiv:astro-ph/0411291 , doi:10.1111/j.1365-2966.2005.08609.x.
6. Rucinski, Slavek M.; et al, Radial Velocity Studies of Close Binary Stars. V., The Astronomical Journal, October 2001, 122 (4): 1974–1980, Bibcode:2001AJ....122.1974R, arXiv:astro-ph/0106160 , doi:10.1086/323106.
7. Li, K.; et al, The Triple Binary Star EQ Tau with an Active Component, The Astronomical Journal, May 2014, 147 (5): 8, Bibcode:2014AJ....147...98L, S2CID 123566937, doi:10.1088/0004-6256/147/5/98 , 98.
8. EQ Tau. SIMBAD. 斯特拉斯堡天文资料中心.
9. Shapley, Harlow; Hughes, Emily M., Variable stars in high galactic latitudes, Annals of the Astronomical Observatory of Harvard College, 1940, 90 (4): 163–175, Bibcode:1940AnHar..90..163S.
10. Artiukhina, N. M., Proper Motions of three W UMa Type Stars in the Pleiades Region, Peremennye Zvezdy, 1961, 13: 366, Bibcode:1961PZ.....13..366A （俄语）.
11. Whitney, B. S., The Period of EQ Tauri, Information Bulletin on Variable Stars, February 1972, 633 (1): 1, Bibcode:1972IBVS..633....1W.
12. Benbow, W. R.; Mutel, R. L., Eclipse Observations of EQ Tau, Information Bulletin on Variable Stars, May 1995, 4187 (1): 1, Bibcode:1995IBVS.4187....1B.
13. Pribulla, T.; Vanko, M., Photoelectric photometry of eclipsing contact binaries: U Peg, YY CrB, OU Ser and EQ Tau, Contributions of the Astronomical Observatory Skalnate Pleso, April 2002, 32 (1): 79–98, Bibcode:2002CoSka..32...79P.

进阶读物

• Tvardovskyi, D. E., Third components with elliptical orbits in the eclipsing binaries: EQ Tau, IR Cas, IV Cas, RY Aqr & RZ Com, Annales Astronomiae Novae, January 2020, 1: 231–238, Bibcode:2020AANv....1..231T, arXiv:1912.12639 .
• Hasanzadeh, A.; et al, New light curve analysis and period changes of the overcontact binary EQ Tauri, New Astronomy, January 2015, 34: 262–265, Bibcode:2015NewA...34..262H, doi:10.1016/j.newast.2014.07.013.
• Elkhateeb, M. M.; Nouh, M. I., A holistic study of the eclipsing binary EQ Tau (PDF), Journal of Physics and Astronomy Research, 2014, 1 (3): 15 [2022-03-13], arXiv:1406.1661 .^{[失效链接]}
• Alton, K. B., A Multi-year Multi-passband CCD Photometric Study of the W UMa Binary EQ Tauri, The Journal of the American Association of Variable Star Observers, December 2009, 37 (2): 148, Bibcode:2009JAVSO..37..148A.
• Hrivnak, Bruce J.; Lu, Wenxian; Eaton, Jeffery; Kenning, Daniel, Light-Curve Study and Physical Properties of the Contact Binary EQ Tauri, The Astronomical Journal, August 2006, 132 (2): 960–966, Bibcode:2006AJ....132..960H, S2CID 120523899, doi:10.1086/505691 .
• Alton, Kevin B., A Backyard CCD Photometric Study of the Neglected W UMa Binary EQ Tauri, Open European Journal on Variable Stars, June 2006, 39: 1, Bibcode:2006OEJV...39....1A.
• Vaňko, M.; et al, New Parameters of the Contact Binary Systems YY CRB and EQ Tau, Baltic Astronomy, 2004, 13: 151–155, Bibcode:2004BaltA..13..151V.
• Yang, Yulan; Liu, Qingyao, A Photometric Study of the Contact Binary EQ Tauri, The Astronomical Journal, December 2002, 124 (6): 3358–3363, Bibcode:2002AJ....124.3358Y, S2CID 123447240, doi:10.1086/344763 .
• Qian, Shengbang; Ma, Yuan, Period Studies of Some Neglected Close Binaries: EP Andromedae, V724 Aquilae, SS Comae, AM Eridani, FZ Orionis, BY Pegasi, EQ Tauri, and NO Vulpeculae, The Publications of the Astronomical Society of the Pacific, June 2001, 113 (784): 754–763, Bibcode:2001PASP..113..754Q, S2CID 121169370, doi:10.1086/320808 .
• Buckner, M.; et al, Eclipse Timing Observations of Three Close Binaries, Information Bulletin on Variable Stars, February 1998, 4559 (1): 1, Bibcode:1998IBVS.4559....1B.