Beta Lacertae

Beta Lacertae (Beta Lac, β Lacertae, β Lac) is the fourth-brightest star in the constellation of Lacerta. Based upon an annual parallax shift of 19.19 mas,^[1] it is 170 light-years distant from Earth. At that distance, the visual magnitude is diminished by an extinction factor of 0.17 due to interstellar dust.^[6]

β Lacertae

β Lacertae in optical light
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Lacerta
Right ascension	22h 23m 33.624s[1]
Declination	+52° 13′ 44.56″[1]
Apparent magnitude (V)	4.43[2]
Characteristics
Evolutionary stage	red clump[3]
Spectral type	G8 III[4]
U−B color index	+0.77[5]
B−V color index	+1.02[5]
V−R color index	0.6[2]
R−I color index	+0.57[5]
Astrometry
Radial velocity (Rv)	−10.4 ± 0.9[2] km/s
Proper motion (μ)	RA: −13.25±0.13[1] mas/yr Dec.: −186.77±0.13[1] mas/yr
Parallax (π)	19.19±0.16 mas[1]
Distance	170 ± 1 ly (52.1 ± 0.4 pc)
Absolute magnitude (MV)	+0.67[6]
Details[6]
Mass	0.97±0.21[4] M☉
Radius	10.96±0.23[4] R☉
Luminosity	57.7±3.0[4] L☉
Surface gravity (log g)	2.43 cgs
Temperature	4803±75[4] K
Metallicity [Fe/H]	−0.33 dex
Rotational velocity (v sin i)	< 17[5] km/s
Age	6.76±3.59[4] Gyr
Other designations
β Lac, Beta Lacertae, Beta Lac, 3 Lacertae, 3 Lac, BD+51 3358, FK5 844, GC 31310, HD 212496, HIP 110538, HR 8538, NLTT 53741, PPM 40598, SAO 34395[2]
Database references
SIMBAD	data

This is an evolved G-type giant with an apparent visual magnitude of approximately 4.43.^[2] It is a red clump^[3] star and the primary component of a suspected binary system, with the pair having an angular separation of 0.2 arcsecond.^[7]

Naming

In Chinese, 螣蛇 (Téng Shé), meaning Flying Serpent, refers to an asterism consisting of β Lacertae, α Lacertae, 4 Lacertae, π² Cygni, π¹ Cygni, HD 206267, ε Cephei, σ Cassiopeiae, ρ Cassiopeiae, τ Cassiopeiae, AR Cassiopeiae, 9 Lacertae, 3 Andromedae, 7 Andromedae, 8 Andromedae, λ Andromedae, κ Andromedae, ι Andromedae and ψ Andromedae. Consequently, the Chinese name for β Lacertae itself is 螣蛇十 (Téng Shé shí, English: the Tenth Star of Flying Serpent).^[8]