座旗五

座旗五（ψ²Aurigae/御夫座ψ²），是御夫座的一顆恆星。視星等4.79^[2]，以裸眼觀測較為黯淡。因為星際氣體及塵埃而產生的消光，其亮度減少了0.07^[5]。

Psi² Aurigae

御夫座ψ2的位置(圈起處)
觀測資料 曆元 J2000
星座	御夫座
星官
赤經	06h 39m 19.82634s[1]
赤緯	+42° 29′ 19.9617″[1]
視星等（V）	4.79[2]
特性
光譜分類	K3 III[3] or K3 Iab:[4]
U−B 色指數	+1.30[2]
B−V 色指數	+1.23[2]
R−I 色指數	0.6
天體測定
徑向速度 (Rv)	16.09 ± 0.19[5] km/s
自行 (μ)	赤經：-0.87[1] mas/yr 赤緯：-54.97[1] mas/yr
視差 (π)	7.84 ± 0.29[1] mas
距離	420 ± 20 ly (128 ± 5 pc)
詳細資料
半徑	27[6] R☉
表面重力 (log g)	2.30[7]
溫度	4,410[7] K
金屬量 [Fe/H]	–0.10[7] dex
自轉速度 (v sin i)	1.0[8] km/s
其他命名
50 Aurigae, BD+42 1585, HD 47174, HIP 31832, HR 2427, SAO 41239.[9]

根據多項研究表明，由恆星光譜可得座旗五為一顆 K3 III 型巨星^[3]，可是根據 2003 年的研究上座旗五被分類為 K3 Iab 型的超巨星^[4][9]。經過周邊昏暗修正的角直徑測量數據為 1.97 ± 0.02 mas^[10]。估計這顆恆星距離^[1]地球為 27 倍的太陽半徑^[6]。

參考資料

1. van Leeuwen, Floor, Validation of the new Hipparcos reduction, Astronomy and Astrophysics, November 2007, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752v1 , doi:10.1051/0004-6361:20078357. Note: see VizieR catalogue I/311 Archive.is的存檔，存檔日期2012-12-05.
2. 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. Herbig, George H.; Spalding, John F., Jr., Axial Rotation and Line Broadening in Stars of Spectral Types F0-K5, Astrophysical Journal, January 1955, 121: 118, Bibcode:1955ApJ...121..118H, doi:10.1086/145969.
4. Kidger, Mark R.; Martín-Luis, Fabiola, High-Precision Near-Infrared Photometry of a Large Sample of Bright Stars Visible from the Northern Hemisphere, The Astronomical Journal, June 2003, 125 (6): 3311–3333, Bibcode:2003AJ....125.3311K4 請檢查|bibcode=值 (幫助), doi:10.1086/374996.
5. Famaey, B.; et al, Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters, Astronomy and Astrophysics, January 2005, 430 (1): 165–186, Bibcode:2005A&A...430..165F, arXiv:astro-ph/0409579 , doi:10.1051/0004-6361:20041272.
6. Lang, Kenneth R., Astrophysical formulae, Astronomy and astrophysics library 1 3, Birkhäuser, 2006 [2013-12-16], ISBN 3-540-29692-1, （原始內容存檔於2013-06-22）. The radius (R_*) is given by:

   ${\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(128\cdot 1.97\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 54\cdot R_{\bigodot }\end{aligned}}}$

7. McWilliam, Andrew, High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances, Astrophysical Journal Supplement Series, December 1990, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527.
8. De Medeiros, J. R.; et al, Rotation and lithium in single giant stars, Astronomy and Astrophysics, November 2000, 363: 239–243, Bibcode:2000A&A...363..239D, arXiv:astro-ph/0010273 .
9. 50 Aur -- Star in double system, SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), [2012-08-24], （原始內容存檔於2021-07-30）.
10. Richichi, A.; Percheron, I.; Khristoforova, M., 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.