Omicron2 Orionis

Omicron2 Orionis (ο2 Ori) is a solitary[7] star in the constellation Orion. It has an apparent visual magnitude of 4.06,[2] which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 17.54 mas, it is around 186 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an interstellar absorption factor of 0.09 due to intervening dust.[8]

For other stars with this Bayer designation, see ο Orionis.
ο2 Orionis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Orion
Right ascension 04h 56m 22.27612s[1]
Declination +13° 30′ 52.0932″[1]
Apparent magnitude (V) 4.06[2]
Characteristics
Spectral type K2 IIIb[3]
U−B color index +1.14[2]
B−V color index +1.17[2]
Astrometry
Radial velocity (Rv)2.54±0.15[4] km/s
Proper motion (μ) RA: −74.88[1] mas/yr
Dec.: −44.33[1] mas/yr
Parallax (π)17.54 ± 0.21 mas[1]
Distance186 ± 2 ly
(57.0 ± 0.7 pc)
Absolute magnitude (MV)0.501[5]
Details[4]
Radius15 R☉
Luminosity79 L☉
Surface gravity (log g)2.4 cgs
Temperature4,498 K
Metallicity [Fe/H]−0.26 dex
Rotational velocity (v sin i)0.0 km/s
Age5.42±2.38[5] Gyr
Other designations
ο2 Ori, 9 Orionis, BD+13° 740, HD 31421, HIP 22957, HR 1580, SAO 94218.[6]
Database references
SIMBADdata

This is a red clump[5] giant star with a stellar classification of K2 IIIb.[3] It is around 5.4[5] billion years old with a projected rotational velocity that is too small to be measured. The star has expanded to about 15 times the radius of the Sun and shines with 79 times the solar luminosity from its outer atmosphere at an effective temperature of 4,498 K.[4] Omicron2 Orionis is most likely a member of the Milky Way's thin disk population.[5]

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, S2CID 18759600.
  2. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
  3. Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 23, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114, 88.
  4. Massarotti, Alessandro; et al. (January 2008), "Rotational and radial velocities for a sample of 761 HIPPARCOS giants and the role of binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209, S2CID 121883397.
  5. Soubiran, C.; et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics, 480 (1): 91–101, arXiv:0712.1370, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788, S2CID 16602121.
  6. "* omi02 Ori". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-11-14.{{cite web}}: CS1 maint: postscript (link)
  7. 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, S2CID 14878976.
  8. Famaey, B.; et al. (2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430: 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272, S2CID 17804304.
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