水位增六

水位增六（巨蟹座Mu²）是一顆單獨的黃色恆星^[10]，位置在黃道星座的巨蟹座內。它是肉眼可見的恆星，視星等+5.30等^[2]，依據從地球測得的周年視差42.94毫角秒^[1]，這顆恆星與太陽的距離是76光年。水位增六將在60萬年後，以最接近的4.9 pc（16 ly）距離掠過太陽^[11]。

水位增六（巨蟹座Mu²）

觀測資料 曆元 J2000.0
星座	巨蟹座
星官
赤經	08h 07m 45.85574s[1]
赤緯	+21° 34′ 54.5441″[1]
視星等（V）	+5.30[2]
特性
光譜分類	G2 IV[3]
U−B 色指數	+0.21[2]
B−V 色指數	+0.63[2]
天體測定
徑向速度 (Rv)	2998640000000000000♠−36.0±0.1[4] km/s
自行 (μ)	赤經：+23.00[1] mas/yr 赤緯：−66.42[1] mas/yr
視差 (π)	42.94 ± 0.30[1] mas
距離	76.0 ± 0.5 ly (23.3 ± 0.2 pc)
絕對星等 (MV)	+3.46[5]
詳細資料
質量	7000119200000000000♠1.192+0.017 −0.016[6] M☉
半徑	1.82[7] R☉
表面重力 (log g)	7000397000000000000♠3.97±0.02[6]
亮度	3.45[8] L☉
溫度	7003580900000000000♠5,809±59[6] K
金屬量 [Fe/H]	0.11[6] dex
自轉速度 (v sin i)	7000370000000000000♠3.7±0.3[5] km/s
年齡	7000564000000000000♠5.64+0.35 −0.14[6] Gyr
其他命名
μ Cnc、​10 Cancri、​BD+22° 1862、​FK5 2630、​HD 67228、​HIP 39780、​HR 3176、​SAO 79959[9]
參考資料庫
SIMBAD	資料

估計它的年齡是56億年，它已演化成G型次巨星，類型為C2IV。^[3]。它的質量是1.2倍太陽質量^[6]，和1.8倍的太陽半徑 ^[7]。 水位增六有相對較高的金屬量 – 天文學家所謂的金屬是除了氫和氦之外的其他元素，比太陽的豐度高出29% ^[6]。它的輻射量 太陽亮度的3.45倍3.45^[8]，表面的有效溫度是5,809k^[6]。

參考資料

1. 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. 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. Gray, R. O.; et al, Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I, The Astronomical Journal, July 2006, 132 (1): 161–170, Bibcode:2006AJ....132..161G, arXiv:astro-ph/0603770 , doi:10.1086/504637.
4. de Bruijne, J. H. J.; Eilers, A.-C., Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project, Astronomy & Astrophysics, October 2012, 546: 14, Bibcode:2012A&A...546A..61D, arXiv:1208.3048 , doi:10.1051/0004-6361/201219219, A61.
5. Ammler-von Eiff, M.; Reiners, A., New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?, Astronomy & Astrophysics, June 2012, 542: 31, Bibcode:2012A&A...542A.116A, arXiv:1204.2459 , doi:10.1051/0004-6361/201118724, A116.
6. Ramírez, I.; et al, Oxygen abundances in nearby FGK stars and the galactic chemical evolution of the local disk and halo, The Astrophysical Journal, February 2013, 764 (1): 78, Bibcode:2013ApJ...764...78R, arXiv:1301.1582 , doi:10.1088/0004-637X/764/1/78.
7. Takeda, Genya; et al, Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog, The Astrophysical Journal Supplement Series, February 2007, 168 (2): 297–318, Bibcode:2007ApJS..168..297T, arXiv:astro-ph/0607235 , doi:10.1086/509763.
8. McDonald, I.; et al, Fundamental Parameters and Infrared Excesses of Hipparcos Stars, Monthly Notices of the Royal Astronomical Society, 2012, 427 (1): 343–57, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037 , doi:10.1111/j.1365-2966.2012.21873.x.
9. mu.02 Cnc. SIMBAD. 斯特拉斯堡天文資料中心. [2017-06-17].
10. 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.
11. Bailer-Jones, C. A. L., Close encounters of the stellar kind, Astronomy & Astrophysics, March 2015, 575: 13, Bibcode:2015A&A...575A..35B, arXiv:1412.3648 , doi:10.1051/0004-6361/201425221, A35.