OU Geminorum

OU Geminorum (OU Gem) is a visual binary or possible triple star located in the constellation of Gemini.

OU Geminorum

A visual band light curve for OU Geminorum, adapted from Bopp et al. (1981)[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Gemini
Right ascension	06h 26m 10.2464s[2]
Declination	+18° 45′ 24.896″[2]
Apparent magnitude (V)	6.768[3]
Characteristics
Spectral type	K3Vk[3]
U−B color index	0.662[3]
B−V color index	0.972[3]
Variable type	BY Dra[4]
Astrometry
Radial velocity (Rv)	−8.98±0.10[5] km/s
Proper motion (μ)	RA: −124.020±0.097[2] mas/yr Dec.: −159.335±0.054[2] mas/yr
Parallax (π)	68.46 ± 0.34 mas[2]
Distance	47.6 ± 0.2 ly (14.61 ± 0.07 pc)
Absolute magnitude (MV)	5.93±0.05[3]
Orbit[5]
Primary	OU Gem Aa
Companion	OU Gem Ab
Period (P)	6.991878±0.000004 d
Eccentricity (e)	0.151±0.0024
Periastron epoch (T)	54900.0719±0.0203 JD
Argument of periastron (ω) (secondary)	77.63±1.09°
Semi-amplitude (K1) (primary)	57.09±0.15 km/s
Semi-amplitude (K2) (secondary)	66.22±0.28 km/s
Details[6]
OU Gem Aa
Mass	0.85 M☉
Radius	0.81 R☉
Surface gravity (log g)	4.55 cgs
Temperature	4960 K
OU Gem Ab
Mass	0.71 M☉
Radius	0.65 R☉
Surface gravity (log g)	4.65 cgs
Temperature	4390 K
Other designations
OU Gem, BD+18 1214, GJ 233, HD 45088, HIP 30630, SAO 95677[7]
Database references
SIMBAD	data

The system has an absolute magnitude of 5.93, so at a distance of 48 light years it has an apparent magnitude of 6.77 when viewed from earth. It also has a total proper motion of 0.210"/yr and belongs to the Ursa Major stream.

The system is a much studied BY Draconis variable star with a period of 6.99 days.^[4] The primary star has a spectral type of K3Vk. The secondary star in the system has a surface temperature of 4486±50 K and orbits the primary in about seven days.^[8][9]

References

1. Bopp, B. W.; Noah, P.; Klimke, A.; Hall, D. S.; Henry, G. W. (August 1981). "Photometry of HD 45088 : a new bright BY DRA variable". Publications of the Astronomical Society of the Pacific. 93: 504–506. Bibcode:1981PASP...93..504B. doi:10.1086/130867. S2CID 122130492.
2. Brown, A. G. A.; et al. (2016). "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties". Astronomy and Astrophysics. 595. A2. arXiv:1609.04172. Bibcode:2016A&A...595A...2G. doi:10.1051/0004-6361/201629512. hdl:2445/125903. S2CID 1828208.Gaia Data Release 1 catalog entry
3. Koen, C.; et al. (April 2010). "UBV(RI)_C JHK observations of Hipparcos-selected nearby stars". Monthly Notices of the Royal Astronomical Society. 403 (4): 1949–1968. Bibcode:2010MNRAS.403.1949K. doi:10.1111/j.1365-2966.2009.16182.x.
4. Bopp, B. W. (1980). "HD 45088 as a BY Draconis variable". Publications of the Astronomical Society of the Pacific. 92: 218–220. Bibcode:1980PASP...92..218B. doi:10.1086/130651. S2CID 119915971.
5. Glazunova, L. V.; et al. (2014). "Absolute parameters and chemical composition of the binary star OU Gem". Monthly Notices of the Royal Astronomical Society. 444 (2): 1901–1908. Bibcode:2014MNRAS.444.1901G. doi:10.1093/mnras/stu1576.
6. Fuhrmann, Klaus (2008). "Nearby stars of the Galactic disc and halo - IV". Monthly Notices of the Royal Astronomical Society. 384 (1): 173–224. Bibcode:2008MNRAS.384..173F. doi:10.1111/j.1365-2966.2007.12671.x.
7. "V* OU Gem". SIMBAD. Centre de données astronomiques de Strasbourg.
8. "Aricns 4C00500". Archived from the original on 2012-09-07. Retrieved 2011-10-04.
9. "Multiwavelength optical observations of chromospherically active bina…" (PDF). Archived from the original (PDF) on 2012-12-09.

External links

• Luck, R. Earle (February 2005). "Stars within 15 Parsecs: Abundances for a Northern Sample". The Astronomical Journal. 129 (2): 1063–1083. Bibcode:2005AJ....129.1063L. doi:10.1086/427250.
• Innes, T.V.; et al. (1998). "OU Gem and AT Cap IN 1984/5 (Commissions 27 and 42 of the IAU)". Information Bulletin on Variable Stars. 4569: 1. Bibcode:1998IBVS.4569....1I.
• Mishenina, T.V.; et al. (2010). "The New Absolute Parameters Of Ou Gem – The star Of By Dra Type". Odessa Astronomical Publications. 23: 83. Bibcode:2010OAP....23...83M.
• University of Hamburg, The. "NEXXUS - Search the Gliese Catalogue". Retrieved 3 October 2011.