Tau5 Serpentis

Tau⁵ Serpentis, Latinized from τ⁵ Serpentis, is a star in the constellation of Serpens. The Flamsteed designation for this star is 18 Serpentis.^[3] It has an apparent visual magnitude of 5.93,^[2] which is bright enough to be dimly visible to the naked eye. The star is located at a distance of 169 light years from the Sun based on parallax measurements.^[1]

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

τ⁵ Serpentis

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Serpens
Right ascension	15h 36m 29.240s[1]
Declination	+16° 07′ 08.70″[1]
Apparent magnitude (V)	5.93[2]
Characteristics
Spectral type	F3V[3]
U−B color index	+0.04[4]
B−V color index	+0.354±0.004[2]
Astrometry
Radial velocity (Rv)	−2.0±3.7[5] km/s
Proper motion (μ)	RA: 72.175 mas/yr[1] Dec.: −5.217 mas/yr[1]
Parallax (π)	19.2694±0.0392 mas[1]
Distance	169.3 ± 0.3 ly (51.9 ± 0.1 pc)
Absolute magnitude (MV)	+2.35[2]
Details
Mass	1.54[5] M☉
Luminosity	10[2] L☉
Surface gravity (log g)	3.96[5] cgs
Temperature	6,903±80[5] K
Metallicity [Fe/H]	−0.20[5] dex
Rotational velocity (v sin i)	88±10[6] km/s
Age	1.90[5] Gyr
Other designations
τ5 Ser, 18 Serpentis, BD+16°2807, GC 20985, HD 139225, HIP 76424, HR 5804, SAO 101642, PPM 131544[3]
Database references
SIMBAD	data

The stellar classification of this star is F3V,^[3] matching an F-type main-sequence star. It has 1.54 times the mass of the Sun^[5] and is radiating 10^[2] times the Sun's luminosity from its photosphere at an effective temperature of 6,903 K.^[5] The star has an estimated age of 1.9 billion years^[5] and is spinning with a projected rotational velocity of about 88 km/s.^[6] It is metal poor, which means the abundance of iron in the stellar atmosphere is lower than in the Sun.^[5]