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]