观测资料 历元 J2000 | |
---|---|
星座 | 巨蛇座 |
星官 | |
赤经 | 18h 21m 18.60056s[1] |
赤纬 | –02° 53′ 55.7766″[1] |
视星等(V) | 3.260[2] |
特性 | |
光谱分类 | K0 III-IV[3] |
U−B 色指数 | +0.643[2] |
B−V 色指数 | +0.940[2] |
天体测定 | |
径向速度 (Rv) | +8.4[4] km/s |
自行 (μ) | 赤经:–547.75[1] mas/yr 赤纬:–701.42[1] mas/yr |
视差 (π) | 53.93 ± 0.18[1] mas |
距离 | 60.5 ± 0.2 ly (18.54 ± 0.06 pc) |
绝对星等 (MV) | +1.87[5] |
详细资料 | |
质量 | 2.0[6] M☉ |
半径 | 5.897 ± 0.028[7] R☉ |
表面重力 (log g) | 3.21[3] |
亮度 | 19 ± 1[8] L☉ |
温度 | 4,890[3] K |
金属量 [Fe/H] | –0.42[3] dex |
自转速度 (v sin i) | 2.6[9] km/s |
其他命名 | |
参考数据库 | |
SIMBAD | data |
天市左垣八(巨蛇座η),也称为东海,是在88星座的巨蛇座中的一颗恒星。比较特别是它位于尾部,视星等为3.26等[2],是巨蛇座的第二亮星,肉眼就可以看见。视差测量估计它与地球的距离是60.5光年(18.5秒差距)[1]。 这颗恒星比太阳大,质量为太阳的2倍,直径是太阳的6倍[6][7]。光谱与分类的K0 III-IV吻合[3],光度分类对应于恒星演化阶段的次巨星和巨星。膨胀的恒星外层光度在有效温度4,890K是太阳的19倍[3]。在这个温度下,它有典型的K型恒星的橙色色调[11]。它有周期为0.09日的类太阳震荡 [12]。
天市左垣八以前被归类为碳星,这使它成为天空中最亮的碳星但目前已经知道这种分类是错误的[13]。
名称
在中国,这颗恒星属于星官天市左垣 (Tiān Shì Zuǒ Yuán),意思是天上市场左边的城墙,也是中国旧有的11个诸侯属地之一。天市左垣包含的恒星有巨蛇座η、武仙座δ、武仙座λ、武仙座μ、武仙座ο、武仙座112、蛇夫座η、宝瓶座ζ、巨蛇座θ1、蛇夫座ν和蛇夫座ξ [14]。因此,它也称为天市左垣八 (Tiān Shì Zuǒ Yuán bā,意思是天上市场左侧第八颗恒星,对应于东海的地区[15][16],可能就是指中国的东海 [来源请求]。
参考资料
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F., Validation of the new Hipparcos reduction, Astronomy and Astrophysics, 2007-11, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752 , doi:10.1051/0004-6361:20078357
- ↑ 2.0 2.1 2.2 2.3 Cousins, A. W. J., Standardization of Broadband Photometry of Equatorial Standards, South African Astronomical Observatory Circulars, 1984, 8: 59, Bibcode:1984SAAOC...8...59C
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Frasca, A.; et al, REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion. Rotation periods and starspot parameters, Astronomy and Astrophysics, 2009-12, 508 (3): 1313–1330, Bibcode:2009A&A...508.1313F, arXiv:0911.0760 , doi:10.1051/0004-6361/200913327
- ↑ Wielen, R.; et al, Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, 1999, Bibcode:1999VeARI..35....1W
- ↑ Carney, Bruce W.; et al, Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars, The Astronomical Journal, 2008-03, 135 (3): 892–906, Bibcode:2008AJ....135..892C, arXiv:0711.4984 , doi:10.1088/0004-6256/135/3/892
- ↑ 6.0 6.1 Edvardsson, B., Spectroscopic surface gravities and chemical compositions for 8 nearby single sub-giants, Astronomy and Astrophysics, 1988-01, 190 (1-2): 148–166, Bibcode:1988A&A...190..148E
- ↑ 7.0 7.1 Mérand, A.; et al, Interferometric radius and limb darkening of the asteroseismic red giant η Serpentis with the CHARA Array, Astronomy and Astrophysics, 2010-07, 517: A64, Bibcode:2010A&A...517A..64M, doi:10.1051/0004-6361/200912103
- ↑ Piau, L.; et al, Surface convection and red-giant radius measurements, Astronomy and Astrophysics, 2011-02, 526: A100, Bibcode:2011A&A...526A.100P, arXiv:1010.3649 , doi:10.1051/0004-6361/201014442
- ↑ Massarotti, Alessandro; et al, Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity, The Astronomical Journal, 2008-01, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209
- ↑ eta Ser -- Variable Star, SIMBAD (Centre de Données astronomiques de Strasbourg), [2012-01-19]
- ↑ The Colour of Stars, Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), 2004-12-21 [2012-01-16]
- ↑ Tabur, V.; et al, Period-luminosity relations of pulsating M giants in the solar neighbourhood and the Magellanic Clouds, Monthly Notices of the Royal Astronomical Society, 2010-12, 409 (2): 777–788, Bibcode:2010MNRAS.409..777T, arXiv:1007.2974 , doi:10.1111/j.1365-2966.2010.17341.x
- ↑ Antipova, L. I.; Boyarchuk, A. A. The chemical composition of the red giant η Ser. Astronomy Reports. 2001, 45 (9): 700. Bibcode:2001ARep...45..700A. doi:10.1134/1.1398919.
- ↑ (中文) 中国星座神话, written by 陈久金. Published by 台湾书房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- ↑ (中文) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育资讯网 2006 年 6 月 23 日
- ↑ (中文) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name , Hong Kong Space Museum. Accessed on line November 23, 2010.