Omega Geminorum

ω Geminorum
	Location of ω Geminorum (circled)
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Gemini
Right ascension	07h 02m 24.78033s
Declination	+24° 12′ 55.6051″
Apparent magnitude (V)	5.18
Characteristics
Spectral type	G5 II
U−B color index	+0.68
B−V color index	+0.95
Variable type	Cepheid?
Astrometry
Radial velocity (Rv)	−9.10±0.40 km/s
Proper motion (μ)	RA: −6.74 mas/yr ; Dec.: -0.25 mas/yr
Parallax (π)	2.19±0.26 mas
Distance	approx. 1,500 ly ; (approx. 460 pc)
Absolute magnitude (MV)	−3.41
Details
Mass	5.3 M☉
Radius	55.6 R☉
Luminosity	1,813 L☉
Surface gravity (log g)	1.20 cgs
Temperature	5,090±12 K
Metallicity [Fe/H]	−0.02 dex
Rotational velocity (v sin i)	10 km/s
Age	14.8 Myr
Other designations
	ω Gem, 42 Geminorum, BD+24°1502, FK5 1182, HD 52497, HIP 33927, HR 2630, SAO 78999.
Database references
SIMBAD	data

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, 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, it is located about 1,500 light years from the Sun.

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

References

1 2 3 4 5 6 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.
1 2 3 4 Argue, A. N. (1966), "UBV photometry of 550 F, G and K type stars", Monthly Notices of the Royal Astronomical Society, 133 (4): 475–493, Bibcode:1966MNRAS.133..475A, doi:10.1093/mnras/133.4.475.
1 2 3 4 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, S2CID 118629873.
1 2 Henriksson, G. (January 1977), "Low amplitude variable stars", Astronomy and Astrophysics, 54: 309–310, Bibcode:1977A&A....54..309H.
↑ 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, S2CID 59451347, A61.
1 2 3 4 5 Usenko, I. A. (April 2017), "Spectroscopic studies of yellow supergiants in the Cepheid instability strip", Astronomy Letters, 43 (4): 265–283, Bibcode:2017AstL...43..265U, doi:10.1134/S1063773717040090, ISSN 1063-7737.
1 2 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, S2CID 118665352.
1 2 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, S2CID 119204089.
↑ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1): 1, Bibcode:1970CoAsi.239....1B.
↑ "ome Gem -- Cepheid variable Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-09.
↑ 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.
↑ Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039
↑ Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R_*) is given by:
$\begin{matrix} 2 \cdot R_{*} & = \frac{(457 \cdot 1.47 \cdot 1 0^{- 3}) AU}{0.0046491 AU / R_{⨀}} \\ \approx 144 \cdot R_{⨀} \end{matrix}$

External links

Kaler, James B., "Omega Geminorum", Stars, University of Illinois, retrieved 2016-12-10.

[vanLeeuwen2007-1] 1 2 3 4 5 6 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.

[Argue1966-2] 1 2 3 4 Argue, A. N. (1966), "UBV photometry of 550 F, G and K type stars", Monthly Notices of the Royal Astronomical Society, 133 (4): 475–493, Bibcode:1966MNRAS.133..475A, doi:10.1093/mnras/133.4.475.

[Tetzlaff2011-3] 1 2 3 4 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, S2CID 118629873.

[Henriksson1977-4] 1 2 Henriksson, G. (January 1977), "Low amplitude variable stars", Astronomy and Astrophysics, 54: 309–310, Bibcode:1977A&A....54..309H.

[aa546_A61-5] 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, S2CID 59451347, A61.

[Usenko2017-6] 1 2 3 4 5 Usenko, I. A. (April 2017), "Spectroscopic studies of yellow supergiants in the Cepheid instability strip", Astronomy Letters, 43 (4): 265–283, Bibcode:2017AstL...43..265U, doi:10.1134/S1063773717040090, ISSN 1063-7737.

[Mcdonald2012-7] 1 2 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, S2CID 118665352.

[Kovtyukh2008-8] 1 2 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, S2CID 119204089.

[Bernacca1970-9] Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1): 1, Bibcode:1970CoAsi.239....1B.

[SIMBAD-10] "ome Gem -- Cepheid variable Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-09.

[Gorynya1998-11] 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.

[Richichi2005-12] Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039

[lang2006-13] Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R_*) is given by:
$\begin{matrix} 2 \cdot R_{*} & = \frac{(457 \cdot 1.47 \cdot 1 0^{- 3}) AU}{0.0046491 AU / R_{⨀}} \\ \approx 144 \cdot R_{⨀} \end{matrix}$