6 Equulei

6 Equulei is a probable (95% chance) astrometric binary^[9] star system in the northern constellation of Equuleus, located 440 light years away.^[1] It is barely visible to the naked eye as a dim, white-hued star with an apparent visual magnitude of 6.07.^[2] The system is moving further away from the Earth with a heliocentric radial velocity of +6.9 km/s.^[6] It forms a wide optical double with γ Equulei, at an angular separation of 336 arcseconds in 2011.^[10]

6 Equulei

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Equuleus
Right ascension	21h 10m 31.31410s[1]
Declination	10° 02′ 56.1112″[1]
Apparent magnitude (V)	6.07[2]
Characteristics
Evolutionary stage	main sequence[3][4]
Spectral type	A2 Vs[3] (A1 Si Sr Cr)[5]
U−B color index	+0.04[2]
B−V color index	+0.02[2]
Astrometry
Radial velocity (Rv)	+6.9[6] km/s
Proper motion (μ)	RA: –0.982 mas/yr[4] Dec.: +17.687 mas/yr[4]
Parallax (π)	7.36±0.81 mas[1]
Distance	approx. 440 ly (approx. 140 pc)
Absolute magnitude (MV)	+0.236[7][better source needed]
Details
Mass	2.412+0.045 −0.047[4] M☉
Radius	2.68±0.08[4] R☉
Luminosity	48.7+1.9 −2.0[4] L☉
Surface gravity (log g)	3.738+0.006 −0.019[4] cgs
Temperature	9,339+32 −118[4] K
Rotational velocity (v sin i)	65[3] km/s
Age	462+75 −71[4] Myr
Other designations
BD+09°4735, HD 201616, HIP 104538, HR 8098, SAO 126597[8]
Database references
SIMBAD	data

The visible component is an Ap star^[3] with a stellar classification of A2Vs,^[3] matching the evolutionary state of an A-type main sequence star while displaying "sharp" absorption lines. It is an estimated 460 million years old^[4] with a projected rotational velocity of 65 km/s.^[3] The star has 2.4 times the mass of the Sun and around 2.7 times the Sun's radius. It is radiating 49 times the luminosity of the Sun from its photosphere at an effective temperature of 9,339 K.^[4]