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上輔Lambda Draconisλ Draconis,縮寫為Lam Draλ Dra),也稱為Giausar[12],位於拱極星座天龍座內,是一顆單獨[13]、呈現橘紅色[14]恆星。它的視星等為 +3.8等,可以用裸眼直接看見[2]。依據從地球上測量到的視差9,79mas [1],這顆恆星距離太陽約333光年

上輔(天龍座λ)
Draco constellation map.svg
Red circle.svg



上輔的位置(紅圈)
觀測資料
曆元 J2000.0
星座 天龍座
星官 紫微右垣(紫微垣)
赤經 11h 31m 24.22075s[1]
赤緯 +69° 19′ 51.8696″[1]
視星等(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]
变星类型慢不規則[4]
天体测定
徑向速度 (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]
詳細資料
質量1.7[7] M
半徑71[8] R
表面重力 (log g)1.10±0.05[9]
亮度834[10] L
溫度3,958[10] K
其他命名
λ Dra1 DraconisBD−70° 665、FK5 433、HD 100029、HIP 56211、HR 4434、 SAO 15532[11]
參考資料庫
SIMBADdata

這是一顆已經演化漸近巨星分支紅巨星[15],在分類上是MOIII-IIIaCa1[3],並被懷疑是顆週期大約1,100天的慢不規則變星[4]。在修正臨邊昏暗之後,測量所得的角直徑6.43±0.07 mas.[16]。在前述的估計距離上,它的真實半徑大約是太陽半徑的53倍[8],質量是太陽質量的1.7倍[7],來自有效溫度3,958K的光球亮度是太陽亮度的834倍[10]

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參考資料编辑

  1. ^ 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. ^ 2.0 2.1 2.2 2.3 Johnson, H. L.; 等, UBVRIJKL photometry of the bright stars, Communications of the Lunar and Planetary Laboratory, 1966, 4 (99), Bibcode:1966CoLPL...4...99J. 
  3. ^ 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. ^ 4.0 4.1 Samus, N. N.; Durlevich, O. V.; 等, Combined General Catalogue of Variable Stars (GCVS4.2), 2007 [2016-09-30]. 
  5. ^ Famaey, B.; 等, 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. 
  6. ^ Park, Sunkyung; 等, 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. ^ 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. ^ 8.0 8.1 Lang, Kenneth R., Astrophysical formulae, Astronomy and astrophysics library 1 3rd, Birkhäuser, 2006, ISBN 3-540-29692-1.  The radius (R*) is given by:
     
  9. ^ Takagi, Yuhei; 等, 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. ^ 10.0 10.1 10.2 McDonald, I.; 等, 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. 
  11. ^ lam Dra. SIMBAD. 斯特拉斯堡天文資料中心. [2017-05-28]. 
  12. ^ Naming Stars. IAU.org. [16 December 2017]. 
  13. ^ 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. 
  14. ^ 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 
  15. ^ Eggen, O. J. Asymptotic giant branch stars near the sun. The Astronomical Journal. 1992, 104: 275. Bibcode:1992AJ....104..275E. doi:10.1086/116239. 
  16. ^ Richichi, A.; 等, 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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