Omicron Arietis

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Omicron Arietis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Aries
Right ascension  02h 44m 32.97317s[1]
Declination +15° 18′ 42.7085″[1]
Apparent magnitude (V) +5.78[2]
Spectral type B9 Vn[3]
U−B color index −0.21[4]
B−V color index −0.01[4]
Radial velocity (Rv)−2.4±3.3[5] km/s
Proper motion (μ) RA: +3.25[1] mas/yr
Dec.: −14.87[1] mas/yr
Parallax (π)5.49 ± 0.32[1] mas
Distance590 ± 30 ly
(180 ± 10 pc)
Absolute magnitude (MV)−0.51[6]
Mass3.45±0.09[7] M
Radius3.1[8] R
Luminosity248[7] L
Temperature10,715[7] K
Rotational velocity (v sin i)225[9] km/s
Other designations
ο Ari, 37 Arietis, BD+14° 457, HD 17036, HIP 12803, HR 809, SAO 93082[10]
Database references

Omicron Arietis, Latinized from ο Arietis, is the Bayer designation for a single,[2] blue-white hued star in the northern constellation of Aries. It has an apparent visual magnitude of +5.78,[2] which means it is dimly visible to the naked eye. Based upon an annual parallax shift of 5.49 mas as seen from Earth,[1] it is located roughly 590 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.22 due to interstellar dust.[11]

This is a B-type main sequence star with a stellar classification of B9 Vn;[3] the 'n' suffix indicates that it has nebulous absorption lines in its spectrum, which are caused by the Doppler effect and rapid rotation. Indeed, it has a projected rotational velocity of 225 km/s;[9] the star has an estimated 3.45[7] times the mass of the Sun and about 3.1[8] times the Sun's radius. It is radiating energy from its photosphere at 248 times the Sun's luminosity with an effective temperature of 10,715 K.[7]


  1. ^ a b c d e f 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. ^ a b c Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  3. ^ a b Cowley, A. (November 1972), "Spectral classification of the bright B8 stars", Astronomical Journal, 77: 750–755, Bibcode:1972AJ.....77..750C, doi:10.1086/111348.
  4. ^ a b Crawford, D. L. (February 1963), "U, b, v, and Hβ Photometry for the Bright B8- and B9-TYPE Stars", Astrophysical Journal, 137: 530, Bibcode:1963ApJ...137..530C, doi:10.1086/147526.
  5. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  6. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  7. ^ a b c d e Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691.
  8. ^ a b Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (Third ed.), 367: 5211–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  9. ^ a b Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
  10. ^ "omi Ari". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-09-28.
  11. ^ Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035.

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