Tau2 Serpentis

Tau² Serpentis, Latinized from τ² Serpentis, is a star in the constellation of Serpens, located approximately 480 light-years from the Sun.^[1] It is a challenge to view with the naked eye, having an apparent visual magnitude of 6.22.^[2] The star is drifting closer with a radial velocity of −19 km/s.^[2]

For other stars with this Bayer designation, see Tau Serpentis.

τ² Serpentis

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Serpens
Right ascension	15h 32m 09.67495s[1]
Declination	+16° 03′ 22.2056″[1]
Apparent magnitude (V)	6.22[2]
Characteristics
Spectral type	B9V[3]
U−B color index	−0.23[4]
B−V color index	−0.038±0.005[2]
Astrometry
Radial velocity (Rv)	−19.3±2.7[2] km/s
Proper motion (μ)	RA: −2.92[5] mas/yr Dec.: +6.48[5] mas/yr
Parallax (π)	6.7936±0.0928 mas[1]
Distance	480 ± 7 ly (147 ± 2 pc)
Absolute magnitude (MV)	+0.44[2]
Details
Mass	2.89±0.08[6] M☉
Radius	2.7[7] R☉
Luminosity	96.4+15.3 −12.6[6] L☉
Temperature	10,839+60 −50[6] K
Rotational velocity (v sin i)	154[6] km/s
Age	278[8] Myr
Other designations
τ2 Ser, 12 Serpentis, BD+16°2797, GC 20880, HD 138527, HIP 76069, HR 5770, SAO 101600, PPM 131484[9]
Database references
SIMBAD	data

This object is a late B-type main-sequence star with a stellar classification of B9V.^[3] It is a probable Lambda Boötis star.^[2][10] The star is 278^[8] million years old and is spinning with a projected rotational velocity of 154 km/s.^[6] It has nearly three times the mass and radius of the Sun.^[6][7] Tau² Serpentis is radiating 96^[6] times the Sun's luminosity from its photosphere at an effective temperature of 10,839 K.^[6]

There is evidence of a possible companion, which is contributing about 15% to the total emission of the system.^[11]