上輔

上輔（Lambda Draconis、λ Draconis，縮寫為Lam Dra、λ Dra），也稱為Giausar，位於拱極星座天龍座內，是一顆單獨、呈現橘紅色的恆星。它的視星等為 +3.8等，可以用裸眼直接看見。依據從地球上測量到的視差9,79mas ，這顆恆星距離太陽約333光年。 這是一顆已經演化至漸近巨星分支的紅巨星，在分類上是MOIII-IIIaCa1，並被懷疑是顆週期大約1,100天的慢不規則變星。在修正臨邊昏暗之後，測量所得的角直徑為7000643000000000000♠6.43±0.07 mas.。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，質量是太陽質量的1.7倍，來自有效溫度3,958K的光球亮度是太陽亮度的834倍。 美國海軍巨爵級貨船（英语：Crater class cargo ship）USS Giansar (AK-111)（英语：USS Giansar (AK-111)）以這顆恆星命名。 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.  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.  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.  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.  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.  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: 2 ⋅ R ∗ = ( 102.1 ⋅ 6.43 ⋅ 10 − 3 )   AU 0.0046491   AU / R ⨀ ≈ 141.2 ⋅ R ⨀ {\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(102.1\cdot 6.43\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 141.2\cdot R_{\bigodot }\end{aligned}}} 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.  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. 斯特拉斯堡天文資料中心. [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.  引用错误：在<references>标签中name属性为“Kaler”的参考文献没有在文中使用 引用错误：在<references>标签中name属性为“Allen1963”的参考文献没有在文中使用