上辅
上辅（Lambda Draconis、λ Draconis，缩写为Lam Dra、λ Dra），也称为Giausar[12]，位于拱极星座天龙座内，是一颗单独[13]、呈现橘红色[14]的恒星。它的视星等为 +3.8等，可以用裸眼直接看见[2]。依据从地球上测量到的视差9,79mas [1]，这颗恒星距离太阳约333光年。
  | |
| 观测资料 历元 J2000.0 | |
|---|---|
| 星座 | 天龙座 |
| 星官 | 紫微右垣（紫微垣） |
| 赤经 | 11h 31m 24.22075s[1] |
| 赤纬 | +69° 19′ 51.8696″[1] |
| 视星等（V） | +3.85[2] |
| 特性 | |
| 光谱分类 | M0III-IIIa Ca1[3] |
| U−B 色指数 | +1.97[2] |
| B−V 色指数 | +1.62[2] |
| 变星类型 | 慢不规则[4] |
| 天体测定 | |
| 径向速度 (Rv) | +6.58±0.30[5] km/s |
| 自行 (μ) | 赤经：−40.97[1] mas/yr 赤纬：−19.19[1] mas/yr |
| 视差 (π) | 9.79 ± 0.15[1] mas |
| 距离 | 333 ± 5 ly (102 ± 2 pc) |
| 绝对星等 (MV) | −1.14±0.033[6] |
| 详细资料 | |
| 质量 | 1.7[7] M☉ |
| 半径 | 71[8] R☉ |
| 表面重力 (log g) | 1.10±0.05[9] |
| 亮度 | 834[10] L☉ |
| 温度 | 3,958[10] K |
| 其他命名 | |
| 参考资料库 | |
| SIMBAD | 资料 |
这是一颗已经演化至渐近巨星分支的红巨星[15]，在分类上是MOIII-IIIaCa1[3]，并被怀疑是颗周期大约1,100天的慢不规则变星[4]。在修正临边昏暗之后，测量所得的角直径为6.43±0.07 mas.[16]。在前述的估计距离上，它的真实半径大约是太阳半径的53倍[8]，质量是太阳质量的1.7倍[7]，来自有效温度3,958K的光球亮度是太阳亮度的834倍[10]。
名称
同名物体
美国海军巨爵级货船USS Giansar (AK-111)以这颗恒星命名。
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, 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 Johnson, H. L.; et al, UBVRIJKL photometry of the bright stars, Communications of the Lunar and Planetary Laboratory, 1966, 4 (99), Bibcode:1966CoLPL...4...99J.
- ^ 3.0 3.1 Keenan, Philip C.; McNeil, Raymond C., The Perkins catalog of revised MK types for the cooler stars, Astrophysical Journal Supplement Series, 1989, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
- ^ 4.0 4.1 Samus, N. N.; Durlevich, O. V.; et al, Combined General Catalogue of Variable Stars (GCVS4.2), 2007 [2016-09-30], （原始内容存档于2018-10-10）.
- ^ Famaey, B.; et al, Spectroscopic binaries among Hipparcos M giants,. I. Data, orbits, and intrinsic variations, Astronomy and Astrophysics, 2009, 498 (2): 627–640, Bibcode:2009A&A...498..627F, arXiv:0901.0934 , doi:10.1051/0004-6361/200810698.
- ^ Park, Sunkyung; et al, Wilson-Bappu Effect: Extended to Surface Gravity, The Astronomical Journal, 2013, 146 (4): 73, Bibcode:2013AJ....146...73P, arXiv:1307.0592 , doi:10.1088/0004-6256/146/4/73.
- ^ 7.0 7.1 Gondoin, P., Evolution of X-ray activity and rotation on G-K giants, Astronomy and Astrophysics, December 1999, 352: 217–227, Bibcode:1999A&A...352..217G.
- ^ 8.0 8.1 Lang, Kenneth R., Astrophysical formulae, Astronomy and astrophysics library 1 3rd, Birkhäuser, 2006 [2019-01-20], ISBN 3-540-29692-1, （原始内容存档于2019-05-20）. The radius (R*) is given by:
- ^ Takagi, Yuhei; et al, Age Determinations of Early-M Type Pre-Main Sequence Stars Using a High-Resolution Near-Infrared Spectroscopic Method, Publications of the Astronomical Society of Japan, June 2011, 63 (3): 677–684, Bibcode:2011PASJ...63..677T, doi:10.1093/pasj/63.3.677.
- ^ 10.0 10.1 10.2 McDonald, I.; et al, Fundamental parameters and infrared excesses of Hipparcos stars, Monthly Notices of the Royal Astronomical Society, 2012, 427: 343, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037 , doi:10.1111/j.1365-2966.2012.21873.x.
- ^ lam Dra. SIMBAD. 斯特拉斯堡天文资料中心. [2017-05-28].
- ^ Naming Stars. IAU.org. [2017-12-16]. （原始内容存档于2020-04-11）.
- ^ Eggleton, P. P.; Tokovinin, A. A., A catalogue of multiplicity among bright stellar systems, Monthly Notices of the Royal Astronomical Society, September 2008, 389 (2): 869–879, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878 , doi:10.1111/j.1365-2966.2008.13596.x.
- ^ Moore, Patrick, The Observer’s Year: 366 Nights of the Universe, The Patrick Moore Practical Astronomy Series, Springer Science & Business Media: 285, 2013, ISBN 1447136136
- ^ Eggen, O. J. Asymptotic giant branch stars near the sun. The Astronomical Journal. 1992, 104: 275. Bibcode:1992AJ....104..275E. doi:10.1086/116239.
- ^ Richichi, A.; et al, CHARM2: An updated Catalog of High Angular Resolution Measurements, Astronomy and Astrophysics, February 2005, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
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