Rho Serpentis, Latinized from ρ Serpentis, is a single[11] star in the Caput section of the equatorial Serpens constellation. It has an orange hue and is faintly visible to the naked eye with an apparent visual magnitude of +4.78.[4] The distance to this star is approximately 375 light years based on parallax,[3] but it is drifting closer to the Sun with a radial velocity of −62 km/s.[6]

Rho Serpentis

A light curve for Rho Serpentis, plotted from Hipparcos data[1][2]
Observation data Epoch J2000      Equinox J2000
Constellation	Serpens
Right ascension	15h 51m 15.90985s[3]
Declination	+20° 58′ 40.5166″[3]
Apparent magnitude (V)	4.78[4]
Characteristics
Spectral type	K4.5III[5]
U−B color index	+1.88[4]
B−V color index	+1.54[4]
Astrometry
Radial velocity (Rv)	−61.96[6] km/s
Proper motion (μ)	RA: −53.32[3] mas/yr Dec.: +18.87[3] mas/yr
Parallax (π)	8.70 ± 0.30 mas[3]
Distance	370 ± 10 ly (115 ± 4 pc)
Absolute magnitude (MV)	−0.56[7]
Details
Radius	47.84+0.49 −1.19[8] R☉
Luminosity	491.9±22.3[8] L☉
Surface gravity (log g)	1.68[9] cgs
Temperature	3,930+50 −20[8] K
Metallicity [Fe/H]	−0.08[7] dex
Other designations
ρ Ser, 38 Serpentis, NSV 7300, BD+21°2829, GC 21311, HD 141992, HIP 77661, HR 5899, SAO 84037[10]
Database references
SIMBAD	data

This is an aging giant star with a stellar classification of K4.5III.[5] It is a suspected variable star of unknown type, with an I-band brightness ranging from 3.29 down to 3.44 magnitude.[12] Hipparcos photometry revealed a microvariability with a frequency of 0.17017 cycles per day and an amplitude of 0.0080.[2] With the supply of hydrogen exhausted at its core, it has expanded and now has 48[8] times the Sun's girth. The star is radiating 492[8] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,930 K.[8]

References