5 Aurigae

5 Aurigae is a triple star^[7] system in the northern constellation of Auriga,^[10] located about 195 light years away from the Sun based on parallax.^[1] It is just visible to the naked eye as a dim, yellow-white hued star with an apparent visual magnitude of 5.95.^[2] The system is moving away from the Earth with a heliocentric radial velocity of +6 km/s,^[6] having come within 62.4 light-years some 8.7 million years ago.^[2]

5 Aurigae

Observation data Epoch J2000      Equinox J2000
Constellation	Auriga
Right ascension	05h 00m 18.33887s[1]
Declination	+39° 23′ 40.9241″[1]
Apparent magnitude (V)	5.95[2] (6.02 + 9.50)[3]
Characteristics
Spectral type	F5 V[4]
U−B color index	−0.03[5]
B−V color index	+0.42[5]
Astrometry
Radial velocity (Rv)	+6.0±1.3[6] km/s
Proper motion (μ)	RA: −10.87[1] mas/yr Dec.: −1.08[1] mas/yr
Parallax (π)	16.74±0.71 mas[1]
Distance	195 ± 8 ly (60 ± 3 pc)
Absolute magnitude (MV)	2.07[2]
Orbit[7]
Period (P)	1,598.04±50.35 yr
Semi-major axis (a)	5.379±0.388″
Eccentricity (e)	0.536±0.031
Inclination (i)	56.1±0.8°
Longitude of the node (Ω)	155.4±0.7°
Periastron epoch (T)	3,242.73±8.96
Argument of periastron (ω) (secondary)	333.4±4.5°
Details
5 Aur A
Mass	1.48[8] or 1.70[7] M☉
Luminosity	12.46[2] L☉
Surface gravity (log g)	4.14[8] cgs
Temperature	6,603±225[8] K
Metallicity [Fe/H]	−0.02±0.07[9] dex
Age	2.205[8] Gyr
5 Aur B
Mass	0.82[7] M☉
Other designations
BD+39° 1133, GC 6084, HD 31761, HIP 23261, HR 1599, SAO 57559, PPM 69817, ADS 3589, CCDM J05003+3924, WDS J05003+3924, TYC 2899-369-1[10]
Database references
SIMBAD	data

This was initially discovered to be a binary star system by Otto Struve. The outer pair has an orbital period of 1,598 years with an eccentricity of 0.536.^[7] The magnitude 6.02^[3] primary, component A, is itself a binary system consisting of two stars of similar mass, roughly 1.5 times the mass of the Sun each, with an orbital period of 8.08 years.^[11] It has a stellar classification of F5 V,^[4] matching an F-type main-sequence star.

As of 2017, component B is a magnitude 9.50 star at an angular separation of 4.10″ from the primary along a position angle of 285°.^[3]