HR 3220

This article is about B Carinae. For b¹ Carinae, see V376 Carinae. For b² Carinae, see HD 77370.

HR 3220 is a binary star system in the southern constellation of Carina. It has the Bayer designation B Carinae; HR 3220 is the designation from the Bright Star Catalogue. It has a yellow-white hue and is visible to the naked eye with an apparent visual magnitude of 4.75.^[2] Based upon parallax measurements, it is located at a distance of 59 light years from the Sun. The system is drifting further away with a radial velocity of +24 km/s.^[5]

HR 3220

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Carina
Right ascension	08h 09m 00.56958s[1]
Declination	−61° 18′ 08.5836″[1]
Apparent magnitude (V)	4.75[2]
Characteristics
Evolutionary stage	Blue straggler[3]
Spectral type	F6 V Fe-0.8 CH-0.4[4]
U−B color index	−0.05[2]
B−V color index	+0.44[2]
Astrometry
Radial velocity (Rv)	+23.7[5] km/s
Proper motion (μ)	RA: −113.750[1] mas/yr Dec.: −297.923[1] mas/yr
Parallax (π)	55.3398±0.5399 mas[1]
Distance	58.9 ± 0.6 ly (18.1 ± 0.2 pc)
Absolute magnitude (MV)	+3.19[6]
Orbit[7]
Period (P)	899.3±0.4 d
Semi-major axis (a)	≥39.0±0.7 Gm
Eccentricity (e)	0.119±0.012
Periastron epoch (T)	1,845±18
Argument of periastron (ω) (secondary)	135±5°
Semi-amplitude (K1) (primary)	3.18±0.06 km/s
Details
A
Mass	1.35[3] M☉
Radius	1.50+0.13 −0.06[1] R☉
Luminosity	3.6±0.4[1] L☉
Surface gravity (log g)	4.12[3] cgs
Temperature	6491+127 −259[1] K
Metallicity [Fe/H]	−0.27[3] dex
Rotational velocity (v sin i)	8.8[6] km/s
Age	10[3] Gyr
B
Mass	0.42+0.09 −0.05[3] M☉
Other designations
B Car, CPD−60°1074, FK5 2636, GJ 297.1, HD 68456, HIP 39903, HR 3220, SAO 250131[8]
Database references
SIMBAD	data

This is a single-lined spectroscopic binary system with an orbital period of 2.46 years and an eccentricity of 0.12.^[7] The visible component is an F-type main sequence star with a stellar classification of F6 V Fe-0.8 CH-0.4,^[4] where the suffix notation indicates mild but anomalous underabundances of iron and the methylidyne radical. The secondary is most likely a helium white dwarf with 0.47 times the mass of the Sun. Mass transfer from the white dwarf progenitor has given the primary the spectral signature of a blue straggler that appears much younger than its actual age of about 10 billion years.^[3]