周鼎一
 周鼎一的位置（左上角） | |
| 觀測資料 曆元 J2000 | |
|---|---|
| 星座 | 后发座 |
| 星官 | 周鼎 (角宿) |
| 赤經 | 13h 11m 52.3935s[1] |
| 赤緯 | +27° 52′ 41.459″[1] |
| 視星等（V） | 4.26 |
| 特性 | |
| 光谱分类 | G0V |
| U−B 色指数 | 0.07 |
| B−V 色指数 | 0.57[2] |
| 变星类型 | None |
| 天体测定 | |
| 徑向速度 (Rv) | +6.1[3] km/s |
| 自行 (μ) | 赤经：-801.44[4] mas/yr 赤纬：882.04[4] mas/yr |
| 视差 (π) | 108.725 ± 0.17[4] mas |
| 距离 | 30.00 ± 0.05 ly (9.20 ± 0.01 pc) |
| 绝对星等 (MV) | 4.45 |
| 詳細資料 | |
| 質量 | 1.15[5] M☉ |
| 半徑 | 1.09[5] R☉ |
| 表面重力 (log g) | 4.38[2] |
| 亮度 | 1.42 L☉ |
| 溫度 | 6,029[2] K |
| 金屬量 | [2] |
| 自轉 | ~10 days |
| 自轉速度 (v sin i) | 4.10 ± 0.06[6] km/s |
| 年齡 | (1.5–2.5) × 109[7] 年 |
| 其他命名 | |
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周鼎一 （β Com / 后发座β）是后发座的一颗主序矮星，距离地球约30光年。希臘字母的β通常標示星座中視星等第二亮的星，但是周鼎一比后髮座α（+5.22等）還亮。
這顆恆星與我們的太陽相似，只是還稍微大一點，絕對星等亮一點。觀察色球活動的短期變化，認為這顆恆星經歷著不同的自轉[8]，周期大約在11–13天[6]。這顆恆星表面的活動週期是16.6年，相較於太陽的11年也較長些，但它可能也有9.6年的第二個活動週期[9]。曾經一度認為這顆恆星有顆光譜伴星，但是精準的徑向速度測量排除了這個可能，不僅沒有偵測到行星環繞著它，也沒有證據顯示有塵埃盤的存在。
参考资料
[编辑]- ^ 1.0 1.1 Perryman, M. A. C.; et al. The HIPPARCOS Catalogue. Astronomy & Astrophysics. April 1997, 323: L49–L52. Bibcode:1997A&A...323L..49P.
- ^ 2.0 2.1 2.2 2.3 Mallik, Sushma V. Chromospheric activity in cool stars and the lithium abundance. Astronomy and Astrophysics. October 1998, 338: 623–636. Bibcode:1998A&A...338..623M.
- ^ Wilson, Ralph Elmer. General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. 1953. Bibcode:1953QB901.W495......
- ^ 4.0 4.1 4.2 van Leeuwen, Floor. Hipparcos, the new Reduction of the Raw data. Astrophysics and Space Science Library 350. 2007. Bibcode:2007A&A...474..653V. ISBN 9781402063411. Note: see VizieR catalogue I/311 Archive.is的存檔，存档日期2012-12-05.
- ^ 5.0 5.1 Takeda, G.; et al. Stellar parameters of nearby cool stars. II. Physical properties of ~1000 cool stars from the SPOCS catalog. Astrophysical Journal Supplement Series. 2007, 168: 297–318. Bibcode:2008yCat..21680297T. Note: see VizieR catalogue J/ApJS/168/297 （页面存档备份，存于互联网档案馆）.
- ^ 6.0 6.1 Gray, David F.; Baliunas, Sallie L., The Rotation of the G0 Dwarf beta Comae, Astrophysical Journal, January 1997, 475: 303–312, Bibcode:1997ApJ...475..303G, doi:10.1086/303522
- ^ Mamajek, Eric E.; Hillenbrand, Lynne A. Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics. The Astrophysical Journal. November 2008, 687 (2): 1264–1293. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785.
- ^ Donahue, Robert A.; Baliunas, Sallie L., Evidence of differential surface rotation in the solar-type star HD 114710, Astrophysical Journal, Part 2 - Letters, July 1992, 393 (2): L63–L66, Bibcode:1992ApJ...393L..63D, doi:10.1086/186452
- ^ Baliunas, S. L.; et al, Chromospheric variations in main-sequence stars, Astrophysical Journal, Part 1, January 1995, 438 (1): 269–287, Bibcode:1995ApJ...438..269B, doi:10.1086/175072 See appendix A.
外部链接
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