Omega Geminorum

Omega Geminorum, Latinized from ω Geminorum, is a star located in the middle of the northern zodiac constellation of Gemini. With an apparent visual magnitude of 5.18,[2] it is faintly visible to the naked eye. According to the Bortle scale, it can be viewed from dark suburban skies. With an annual parallax shift of just 2.19 mas,[1] it is located about 1,500 light years from the Sun.

ω Geminorum
Location of ω Geminorum (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Gemini
Right ascension 07h 02m 24.78033s[1]
Declination +24° 12′ 55.6051″[1]
Apparent magnitude (V) 5.18[2]
Characteristics
Spectral type G5 II[3]
U−B color index +0.68[2]
B−V color index +0.95[2]
Variable type Cepheid?[4]
Astrometry
Radial velocity (Rv)−9.10±0.40[5] km/s
Proper motion (μ) RA: −6.74[1] mas/yr
Dec.: -0.25[1] mas/yr
Parallax (π)2.19 ± 0.26[1] mas
Distanceapprox. 1,500 ly
(approx. 460 pc)
Absolute magnitude (MV)−3.06[6]
Details
Mass6.3±0.5[3] M☉
Radius72[7] R☉
Luminosity1,813[8] L☉
Surface gravity (log g)2.45[9] cgs
Temperature5,090[9] K
Metallicity [Fe/H]−0.02[9] dex
Rotational velocity (v sin i)10[10] km/s
Age14.8[3] Myr
Other designations
ω Gem, 42 Geminorum, BD+24° 1502, FK5 1182, HD 52497, HIP 33927, HR 2630, SAO 78999.[11]
Database references
SIMBADdata

This is an evolved bright giant star with a stellar classification of G5 II.[3] It is positioned near the instability strip and in 1977 was listed as a candidate cepheid variable star[12] with a luminosity amplitude of 0.086 and a period of 0.7282 days.[4] The interferometer-measured angular diameter of this star is 1.47±0.21 mas.[13] At its estimated distance, this yields a physical size of about 72 times the radius of the Sun.[7] It has 6.3[3] times the mass of the Sun and radiates 1,813[8] times the solar luminosity from its outer atmosphere at an effective temperature of 5,090 K.[9]

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. Argue, A. N. (1966), "UBV photometry of 550 F, G and K type stars", Monthly Notices of the Royal Astronomical Society, 133: 475–493, Bibcode:1966MNRAS.133..475A, doi:10.1093/mnras/133.4.475.
  3. Tetzlaff, N.; et al. (January 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.
  4. Henriksson, G. (January 1977), "Low amplitude variable stars", Astronomy and Astrophysics, 54: 309–310, Bibcode:1977A&A....54..309H.
  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. 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. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  9. Kovtyukh, V. V.; et al. (September 2008), "Reddenings of FGK supergiants and classical Cepheids from spectroscopic data", Monthly Notices of the Royal Astronomical Society, 389 (3): 1336–1344, arXiv:0807.2057, Bibcode:2008MNRAS.389.1336K, doi:10.1111/j.1365-2966.2008.13644.x.
  10. Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1), Bibcode:1970CoAsi.239....1B.
  11. "ome Gem -- Cepheid variable Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-09.
  12. Gorynya, N. A.; et al. (November 1998), "A catalog of Cepheid radial velocities measured in 1995-1998 with the correlation spectrometer", Astronomy Letters, 24 (6): 815–818, Bibcode:1998AstL...24..815G.
  13. Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431: 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039
  • Kaler, James B., "Omega Geminorum", Stars, University of Illinois, retrieved 2016-12-10.
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