23 Vulpeculae

23 Vulpeculae is a triple star system^[12] in the northern constellation of Vulpecula. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.52^[2] and it is located approximately 327 light years away from the Sun based on parallax.^[1] The system is moving further from the Earth with a heliocentric radial velocity of +1.47 km/s.^[4]

23 Vulpeculae

Location of 23 Vulpeculae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Vulpecula
Right ascension	20h 15m 46.1432s[1]
Declination	27° 48′ 51.116″[1]
Apparent magnitude (V)	4.52[2]
Characteristics
Spectral type	K3- III Fe-1[3]
U−B color index	+1.11[2]
B−V color index	+1.26[2]
Astrometry
Radial velocity (Rv)	+1.47[4] km/s
Proper motion (μ)	RA: −39.938±0.128[1] mas/yr Dec.: 12.121±0.147[1] mas/yr
Parallax (π)	9.9642±0.1698 mas[1]
Distance	327 ± 6 ly (100 ± 2 pc)
Absolute magnitude (MV)	−0.58[5]
Orbit[6]
Primary	23 Vul Aa
Companion	23 Vul Ab
Period (P)	25.33 yr
Semi-major axis (a)	0.111″
Eccentricity (e)	0.400
Inclination (i)	71.5°
Longitude of the node (Ω)	97.5°
Periastron epoch (T)	2009.56
Argument of periastron (ω) (secondary)	293.8°
Details
23 Vul A
Mass	2.4[7] M☉
Radius	31±2[8] R☉
Luminosity	288[8] L☉
Surface gravity (log g)	0.89[9] cgs
Temperature	4,413±125[8] K
Metallicity [Fe/H]	−0.22[8] dex
Rotational velocity (v sin i)	3.7[10] km/s
Other designations
23 Vul, BD+27°3666, GC 28152, HD 192806, HIP 99874, HR 7744, SAO 88428, WDS J20158+2749AB[11]
Database references
SIMBAD	data

Component A forms a binary system with an orbital period of 25.33 years, an eccentricity of 0.40, and a semimajor axis of 0.11″.^[6] The 4.80 magnitude member of this pair, component Aa is an aging giant star with a stellar classification of K3- III Fe-1,^[3] where the suffix indicates an underabundance of iron in the spectrum. This star has 2.4^[7] times the mass of the Sun and is radiating 288 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,413 K.^[8] Its companion, component Ab, has magnitude 6.5.^[6] The tertiary member, component B, has a separation of 0.26" and a magnitude of 6.94.^[7][13][12]