HD 20104

HD 20104 (HR 967) is a visual binary in the northern circumpolar constellation Camelopardalis. The system has a combined apparent magnitude of 6.41,^[9] making it near naked eye visibility. When resolved in a large telescope, HD 20104 appears to be a pair of 7th magnitude A-type main-sequence stars with a separation of about 0.5″.^[10] Located approximately 550 light years away,^[6] the system is approaching the Sun with a heliocentric radial velocity of −6 km/s.^[5]

HD 20104

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Camelopardalis[1]
A
Right ascension	03h 17m 31.527s[2]
Declination	+65° 39′ 30.11″[2]
Apparent magnitude (V)	7.05±0.01[2]
B
Right ascension	03h 17m 31.593s[2]
Declination	+65° 39′ 30.26″[2]
Apparent magnitude (V)	7.39±0.01[2]
Characteristics
A
Spectral type	A2 V[3]
U−B color index	+0.06[4]
B−V color index	+0.08[4]
B
Spectral type	A4V[3]
Astrometry
Radial velocity (Rv)	−6±2[5] km/s
Proper motion (μ)	RA: −10.54 mas/yr[6] Dec.: +5.84 mas/yr[6]
Parallax (π)	5.92±0.65 mas[6]
Distance	approx. 550 ly (approx. 170 pc)
Absolute magnitude (MV)	+0.3[1]
Orbit[7]
Primary	HD 20104 A
Companion	HD 20104 B
Period (P)	350 yr
Semi-major axis (a)	0.46″
Eccentricity (e)	0.4
Inclination (i)	135°
Longitude of the node (Ω)	58°
Periastron epoch (T)	2055.0
Argument of periastron (ω) (secondary)	100°
Details
A
Mass	2.46[8] M☉
B
Mass	2.27[8] M☉
Other designations
BD+65°338, GC 3893, HD 20104, HIP 15309, HR 967, SAO 12686, ADS 2436, WDS J03175+6540
Database references
SIMBAD	The system
	A
	B

The system's stars have masses twice that of the Sun^[8] and effective temperatures ranging from 8,100 to 8,700 K,^[9][11] typical of stars their type. The primary radiates at 71.3 L_☉^[11] − over luminous for its class − and spins with a projected rotational velocity of 159 km/s.^[12] HD 20104 has an age of 313 million years.^[11]