Nu Orionis

Nu Orionis (ν Orionis) is a binary star[11] system in the northeastern part of the constellation Orion. It should not be confused with the variable star NU Orionis.[12] Nu Orionis has an apparent visual magnitude of 4.42,[2] which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 0.00632 arcseconds,[1] the distance to this system is roughly 520 light years.

ν Orionis
Location of ν Orionis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Orion
Right ascension 06h 07m 34.32588s[1]
Declination +14° 46′ 06.5061″[1]
Apparent magnitude (V) 4.42[2]
Characteristics
Spectral type B3 V[3] or B3 IV[4]
U−B color index −0.67[2]
B−V color index −0.18[2]
Astrometry
Radial velocity (Rv)+24.1[5] km/s
Proper motion (μ) RA: +6.78[1] mas/yr
Dec.: −20.23[1] mas/yr
Parallax (π)6.32 ± 0.33[1] mas
Distance520 ± 30 ly
(158 ± 8 pc)
Orbit[6]
Period (P)131.211 d
Eccentricity (e)0.64
Periastron epoch (T)2436475.852 JD
Argument of periastron (ω)
(secondary)		6.6°
Semi-amplitude (K1)
(primary)		33.3 km/s
Details
ν Ori A
Mass6.7±0.1[4] M☉
Radius4.3[7] R☉
Luminosity1,965[3] L☉
Surface gravity (log g)4.06[8] cgs
Temperature17,880[8] K
Metallicity [Fe/H]−0.05[8] dex
Rotational velocity (v sin i)30[9] km/s
Age26.3±5.3[4] Myr
Other designations
ν Ori, 67 Orionis, BD+14° 1152, FK5 232, HD 41753, HIP 29038, HR 2159, SAO 95259.[10]
Database references
SIMBADdata

This is a single-lined spectroscopic binary system,[9] which means that only the absorption line features of one of the components can be distinguished. The components orbit each other with a period of 131.2 days and an eccentricity of 0.64.[6] Depending on the source, the primary is either a B-type main sequence star with a stellar classification of B3 V,[3] or a more evolved B-type subgiant star of class B3 IV.[4] It has an angular diameter of 0.251 mas,[13] which, at the estimated distance of this system, yields a physical size of about 4.3 times the radius of the Sun.[7] The mass is 6.7[4] times that of the Sun and it shines with 1,965[3] times the solar luminosity from its outer atmosphere at an effective temperature of 17,880 K.[8]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. Crawford, D. L.; et al. (1971), "Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere", The Astronomical Journal, 76: 1058, Bibcode:1971AJ.....76.1058C, doi:10.1086/111220.
  3. Hohle, M. M.; et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349–360, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355.
  4. Tetzlaff, N.; et al. (2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x.
  5. Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E.
  6. Pourbaix, D.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213.
  7. Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1.. The radius (R*) is given by:
  8. Gies, Douglas R.; Lambert, David L. (March 1992), "Carbon, nitrogen, and oxygen abundances in early B-type stars", Astrophysical Journal, Part 1, 387: 673–700, Bibcode:1992ApJ...387..673G, doi:10.1086/171116.
  9. Abt, Helmut A.; et al. (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590.
  10. "nu. Ori". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-11-03.
  11. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  12. Marett-Crosby, Michael (2013), Twenty-Five Astronomical Observations That Changed the World: And How To Make Them Yourself, The Patrick Moore Practical Astronomy Series, Springer Science & Business Media, p. 93, ISBN 1461468000.
  13. Zorec, J.; et al. (July 2009), "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff", Astronomy and Astrophysics, 501 (1): 297–320, arXiv:0903.5134, Bibcode:2009A&A...501..297Z, doi:10.1051/0004-6361/200811147.
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