金牛座SZ

金牛座SZ是位于黄道星座金牛座的一颗变星。这颗恒星的亮度接近肉眼可见的下限，以3.149天的周期，在视星等6.39等到6.69星等之间变化^[3]。根据视差的量测，到这颗恒星的距离约为2,070光年^[2]。有迹象表明这可能是一颗联星系统，但证据并不确定^[14]。

金牛座SZ

依据凌日系外行星巡天卫星（TESS） 的数据，绘制的金牛座SZ光变曲线[1]。
观测资料 历元 J2000.0
星座	金牛座
星官
赤经	04h 37m 14.778s[2]
赤纬	+18° 32′ 34.93″[2]
视星等（V）	6.39 to 6.69[3]
特性
演化阶段	超巨星
光谱分类	F5Ib-F9.5Ib[4]
B−V 色指数	0.810+0.025 −[5]
变星类型	仙王座δ[6]
天体测定
径向速度 (Rv)	−1.2+0.2 −[7] km/s
自行 (μ)	赤经：−4.403 mas/yr 赤纬：−5.232 mas/yr
视差 (π)	1.5741 ± 0.028[2] mas
距离	2,070 ± 40 ly (640 ± 10 pc)
详细资料
质量	6.1+0.8 −[8] M☉
半径	42.2+3.0 −[9] R☉
表面重力 (log g)	2.0–2.2[10]
亮度	1,905[11] L☉
温度	6,015–6,420[11] K
金属量 [Fe/H]	0.08[10] dex
年龄	69–80[12] Myr
其他命名
SZ Tau、​BD+18 661、​GC 5621、​HD 29260、​HIP 21517、​SAO 94036、​PPM 120081[13]
参考资料库
SIMBAD	资料

这颗恒星的可变性是由卡尔·史瓦西（英语：Karl Schwarzschild）在1911年宣布的，起初被命名为41.1910，周期为7005272021760000000♠3.1484 d^[15][16]。勒维特（英语：Henrietta Swan Leavitt）将这项研究持续到1914年，产生了一个周期为7005272047680000000♠3.1487 d的光变曲线^[17]。1916年，H.沙普利（英语：Harlow Shapley）的一项光谱研究表明，造父变星的这种恒星脉动（英语：Stellar pulsation）使恒星分类的类型沿著光变曲线变化，从光度最低的F7到最高的A9^[18]。尤里·尼古拉耶维奇·埃夫雷莫夫（英语：Yuri Nicolaevich Efremov）在1964年提出，这颗恒星位于疏散星团NGC 1647的东北方2.2°，可能是其晕成员^[19]。然而，后来因为自行不能吻合而，因而引起争议^[20]。它在1985年被沃尔夫冈·吉伦（英语：Wolfgang Gieren）确认为经典造父变星 ^[21]。

在变星总表中，金牛座SZ被归类为DCEPS型的仙王座δ型变星，它显示出一条几乎对称的小振幅光变曲线^[6]。它在第一个泛音中脉动^[19]，并且在演化方面，正在经历第二次穿越造父变星的不稳定带^[12]。到1987年，已经观察到金牛座SZ脉动周期的四次变化^[22]；脉动频率每年减少-0.49 秒^[12]。这颗星的年龄大约是7,500万年^[12]，质量是太阳的6倍^[8]，半径是太阳的42倍^[9]。恒星的有效温度、半径和光谱类型在每个脉动周期中都会变化^[11]。

参考资料

1. 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）.
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. Klagyivik, P.; Szabados, L., Observational studies of Cepheid amplitudes. I. Period-amplitude relationships for Galactic Cepheids and interrelation of amplitudes, Astronomy and Astrophysics, September 2009, 504 (3): 959–972, Bibcode:2009A&A...504..959K, S2CID 18283579, arXiv:0908.3561 , doi:10.1051/0004-6361/200811464.
4. Kraft, Robert P., Color Excesses for Supergiants and Classical Cepheids. I. Calibration of the Gband Photometry, Astrophysical Journal, March 1960, 131: 330, Bibcode:1960ApJ...131..330K, doi:10.1086/146837.
5. 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.
6. 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.
7. 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.
8. Marconi, Marcella; et al, Predicted Masses of Galactic Cepheids in the Gaia Data Release 2, The Astrophysical Journal Letters, July 2020, 898 (1): L7, Bibcode:2020ApJ...898L...7M, S2CID 220265392, arXiv:2006.16610 , doi:10.3847/2041-8213/aba12b, L7.
9. Postma, Joseph E.; Milone, E. F., Observations and Analyses of the Cepheid SZ Tauri, Bulletin of the American Astronomical Society, June 2006, 38: 144, Bibcode:2006AAS...208.6506P.
10. Andrievsky, S. M.; et al, Barium abundances in Cepheids, Monthly Notices of the Royal Astronomical Society, 2013, 428 (4): 3252, Bibcode:2013MNRAS.428.3252A, arXiv:1210.6211 , doi:10.1093/mnras/sts270 .
11. Sanwal, B. B.; Rautela, B. S., Spectrophotometric Study of the Cepheids DT-Cygni and SZ-Tauri, Astrophysics and Space Science, January 1989, 151 (2): 209–215, Bibcode:1989Ap&SS.151..209S, S2CID 119557969, doi:10.1007/BF00648379.
12. Fadeyev, Yu. A., Evolution, pulsation and period change in the Cepheid SZ Tau, Astronomy Letters, November 2015, 41 (11): 640–645, Bibcode:2015AstL...41..640F, S2CID 255192877, arXiv:1507.04715 , doi:10.1134/S1063773715110031.
13. [

    http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=SZ+Tau

    SZ Tau] 请检查|url=值 (帮助). SIMBAD. 斯特拉斯堡天文资料中心.
14. Kervella, Pierre; et al, Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2. II. Resolved common proper motion pairs, Astronomy & Astrophysics, March 2019, 623: 40, Bibcode:2019A&A...623A.117K, arXiv:1908.00545 , doi:10.1051/0004-6361/201834211, A117.
15. Schwarzschild, Karl, Über den Lichtwechsel des Veränderlichen 41.1910 Tauri, Astronomische Nachrichten, October 1911, 189 (20): 345–356 [2023-08-14], Bibcode:1911AN....189..345S, doi:10.1002/asna.2101892002, （原始内容存档于2023-08-14） （德语）.
16. Shapley, H., Concerning the ellipsoidal variables SZ Tauri and S Antliae, Astronomische Nachrichten, May 1913, 194 (21): 353–359 [2023-08-14], Bibcode:1913AN....194..353S, doi:10.1002/asna.19131942102, （原始内容存档于2023-08-14）.
17. Leavitt, Henrietta S.; Pickering, Edward C., Observations of SZ Tauri, Harvard College Observatory Circular, November 1914, 186: 1–4, Bibcode:1914HarCi.186....1L.
18. Shapley, H., The variations in spectral type of twenty Cepheid variables, Astrophysical Journal, December 1916, 44: 273–291, Bibcode:1916ApJ....44..273S, doi:10.1086/142295.
19. Turner, David G., Galactic Clusters With Associated Cepheid Variables. III. NGC 1647 and SZ Tauri, Astronomical Journal, November 1992, 104: 1865 [2023-08-14], Bibcode:1992AJ....104.1865T, doi:10.1086/116363, （原始内容存档于2023-08-14）.
20. Baumgardt, H.; et al, Absolute proper motions of open clusters. I. Observational data, Astronomy and Astrophysics Supplement, October 2000, 146 (2): 251–258, Bibcode:2000A&AS..146..251B, S2CID 7180188, arXiv:astro-ph/0010306 , doi:10.1051/aas:2000362.
21. Gieren, W. P., Physical properties of the cepheids RT Aurigae and SZ Tauri, Astronomy and Astrophysics, July 1985, 148: 138–144, Bibcode:1985A&A...148..138G.
22. Trammell, Susan R., The Changing Period of SZ Tauri, The Journal of the American Association of Variable Star Observers, December 1987, 16 (2): 104–106, Bibcode:1987JAVSO..16..104T.