水府一

水府一（獵戶座ν）是位於獵戶座東北部的一對聯星^[11]，不要將其與變星獵戶座NU混淆^[12]。水府一的視星等為4.42^[2]，這足夠明亮，因此可以用肉眼直接看到。依據0.00632弧秒的年週視差^[1]，這個系統的距離大約是520光年。

水府一( 獵戶座ν)

水府一的位置(紅圈)
觀測資料 曆元 J2000.0
星座	獵戶座
星官	水府 （參宿）
赤經	06h 07m 34.32588s[1]
赤緯	+14° 46′ 06.5061″[1]
視星等（V）	4.42[2]
特性
光譜分類	B3 V[3] or B3 IV[4]
U−B 色指數	−0.67[2]
B−V 色指數	−0.18[2]
天體測定
徑向速度 (Rv)	+24.1[5] km/s
自行 (μ)	赤經：+6.78[1] mas/yr 赤緯：−20.23[1] mas/yr
視差 (π)	6.32 ± 0.33[1] mas
距離	520 ± 30 ly (158 ± 8 pc)
軌道[6]
繞行週期 (P)	131.211 d
偏心率 (e)	0.64
近心點 曆元 (T)	2436475.852 JD
近心點幅角 (ω) (secondary)	6.6°
半振幅 (K1) (primary)	33.3 km/s
詳細資料
ν Ori A
質量	7000670000000000000♠6.7±0.1[4] M☉
半徑	4.3[7] R☉
表面重力 (log g)	4.06[8]
亮度	1,965[3] L☉
溫度	17,880[8] K
金屬量 [Fe/H]	−0.05[8] dex
自轉速度 (v sin i)	30[9] km/s
年齡	7001263000000000000♠26.3±5.3[4] Myr
其他命名
ν Ori, 67 Orionis, BD+14° 1152, FK5 232, HD 41753, HIP 29038, HR 2159, SAO 95259.[10]
參考資料庫
SIMBAD	資料

這是肘有一組譜線的光譜聯星系統^[9]，這意味著只能分析其中一個成員的吸收譜線特徵。根據這個分量的繞行，週期為131.2天，離心率為0.64^[6]。根據這個來源，主星要麼是恆星分類為B3V的B型主序星^[3]， 或是已經演化成為B3IV的B型次巨星^[4]。 它的角直徑為0.251mas^[13]，以這個系統的距離估計，它的實際半徑約為4.3R_☉（太陽半徑）^[7]，質量是6.7M_☉（太陽質量）^[4]，光度是1,965L_☉（太陽光度）^[3]，大氣層表面的有效溫度為17,880K^[8]。

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, S2CID 18759600, arXiv:0708.1752 , doi:10.1051/0004-6361:20078357.
2. Crawford, D. L.; et al, Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere, The Astronomical Journal, 1971, 76: 1058, Bibcode:1971AJ.....76.1058C, doi:10.1086/111220.
3. Hohle, M. M.; et al, Masses and luminosities of O- and B-type stars and red supergiants, Astronomische Nachrichten, April 2010, 331 (4): 349–360, Bibcode:2010AN....331..349H, S2CID 111387483, arXiv:1003.2335 , doi:10.1002/asna.200911355.
4. Tetzlaff, N.; et al, A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun, Monthly Notices of the Royal Astronomical Society, 2011, 410 (1): 190–200, Bibcode:2011MNRAS.410..190T, S2CID 118629873, arXiv:1007.4883 , doi:10.1111/j.1365-2966.2010.17434.x.
5. Evans, D. S., The Revision of the General Catalogue of Radial Velocities, Batten, Alan Henry; Heard, John Frederick (編), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30 30, University of Toronto: International Astronomical Union: 57, June 20–24, 1966, Bibcode:1967IAUS...30...57E.
6. Pourbaix, D.; et al, S_B⁹: The ninth catalogue of spectroscopic binary orbits, Astronomy and Astrophysics, 2004, 424 (2): 727–732, Bibcode:2004A&A...424..727P, S2CID 119387088, arXiv:astro-ph/0406573 , doi:10.1051/0004-6361:20041213.
7. Lang, Kenneth R., Astrophysical formulae, Astronomy and astrophysics library 1 3rd, Birkhäuser, 2006 [2021-12-06], ISBN 3-540-29692-1, （原始內容存檔於2019-05-20）.. The radius (R_*) is given by:

   ${\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(158.2\cdot 0.251\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 8.5\cdot R_{\bigodot }\end{aligned}}}$

8. Gies, Douglas R.; Lambert, David L., Carbon, nitrogen, and oxygen abundances in early B-type stars, Astrophysical Journal, Part 1, March 1992, 387: 673–700, Bibcode:1992ApJ...387..673G, doi:10.1086/171116.
9. Abt, Helmut A.; et al, Rotational Velocities of B Stars, The Astrophysical Journal, July 2002, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590 .
10. nu. Ori. SIMBAD. 斯特拉斯堡天文資料中心.
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, S2CID 14878976, arXiv:0806.2878 , doi:10.1111/j.1365-2966.2008.13596.x.
12. Marett-Crosby, Michael, Twenty-Five Astronomical Observations That Changed the World: And How To Make Them Yourself, The Patrick Moore Practical Astronomy Series, Springer Science & Business Media: 93, 2013 [2021-12-06], ISBN 978-1461468004, （原始內容存檔於2021-12-06）.
13. Zorec, J.; et al, Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into T_eff, Astronomy and Astrophysics, July 2009, 501 (1): 297–320, Bibcode:2009A&A...501..297Z, S2CID 14969137, arXiv:0903.5134 , doi:10.1051/0004-6361/200811147.