2 Lyncis

2 Lyncis is a binary star system in the northern constellation Lynx. It is visible to the naked eye, having an apparent visual magnitude of 4.44.[2] The distance to this system, judging by an annual parallax shift of 20.83±0.40 mas,[1] is around 157 light years. It is moving closer to the Sun with a heliocentric radial velocity of −2 km/s.[5]

2 Lyncis

2 Lyncis in optical light.
Observation data Epoch J2000      Equinox J2000
Constellation	Lynx
Right ascension	06h 19m 37.38458s[1]
Declination	+59° 00′ 39.4683″[1]
Apparent magnitude (V)	4.44[2]
Characteristics
Spectral type	A2 Vs[3]
B−V color index	0.032±0.004[2]
Variable type	Eclipsing binary[4]
Astrometry
Radial velocity (Rv)	−2.0±0.1[5] km/s
Proper motion (μ)	RA: −5.35[1] mas/yr Dec.: +23.86[1] mas/yr
Parallax (π)	20.83 ± 0.40 mas[1]
Distance	157 ± 3 ly (48.0 ± 0.9 pc)
Absolute magnitude (MV)	1.03[2]
Orbit[6]
Period (P)	1306.82±0.96 d
Eccentricity (e)	0.497±0.010
Periastron epoch (T)	2450962.0±2.0
Argument of periastron (ω) (secondary)	186.30±0.79°
Semi-amplitude (K1) (primary)	3.281±0.044 km/s
Details[6]
2 Lyn A
Mass	2.32±0.02[3] M☉
Radius	2.2 R☉
Luminosity	39.5+1.8 −1.7[3] L☉
Surface gravity (log g)	4.1±0.1 cgs
Temperature	9,310±100 K
Rotation	1.56 d
Rotational velocity (v sin i)	44 km/s
2 Lyn B
Mass	0.46 M☉
Other designations
2 Lyn, UZ Lyn, BD+59° 959, FK5 237, HD 43378, HIP 30060, HR 2238, SAO 25665[7]
Database references
SIMBAD	data

This is a spectroscopic binary star system with an orbital period of around 3.6 years and an eccentricity of 0.5. It is classified as a probable (91% chance) eclipsing binary with the variable star designation UZ Lyn, showing a net magnitude decrease of 0.3 during an occultation.[4]

The primary component is an A-type main-sequence star[6] with a stellar classification of A2 Vs,[3] where the 's' indicates narrow (sharp) absorption lines. The orbiting companion may be the source of the X-ray emission from this system, as stars similar to the primary component do not generally produce detectable levels of X-rays.[8]