Eta Canis Minoris

Eta Canis Minoris is a binary star^[3] system in the equatorial constellation of Canis Minor. Its name is a Bayer designation that is Latinized from η Canis Minoris, and abbreviated Eta CMi or η CMi. The brighter component has an apparent visual magnitude of 5.25,^[2] which indicates it is faintly visible to the naked eye. Based on parallax measurements,^[1] the distance to this system is approximately 319 light-years (98 pc) from the Sun. It is drifting further away with a line of sight velocity of +17 km/s.^[4]

η Canis Minoris

Location of η Canis Minoris (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Canis Minor
Right ascension	07h 28m 02.075s[1]
Declination	+06° 56′ 31.09″[1]
Apparent magnitude (V)	5.25[2] + 11.1[3]
Characteristics
Spectral type	F0 III[3]
U−B color index	+0.17[2]
B−V color index	+0.22[2]
Astrometry
Radial velocity (Rv)	+17.2[4] km/s
Proper motion (μ)	RA: −3.109 mas/yr[1] Dec.: −43.633 mas/yr[1]
Parallax (π)	10.2172±0.1069 mas[1]
Distance	319 ± 3 ly (98 ± 1 pc)
Absolute magnitude (MV)	0.1[5]
Details
η CMi A
Mass	2.16[4] M☉
Luminosity	57.5[4] L☉
Surface gravity (log g)	3.66[6] cgs
Temperature	7,505±66[4] K
Rotational velocity (v sin i)	54[7] km/s
Age	818[6] Myr
Other designations
η CMi, 5 CMi, BD+07°1729, GC 9970, HD 58923, HIP 36265, HR 2851, SAO 115477, ADS 6101, CCDM 07280+0657, WDS J07280+0657A[8]
Database references
SIMBAD	data

The primary component, η Canis Minoris A, is a yellow-white F-type giant with a stellar classification of F0 III.^[3] At the estimated age of 818 million years,^[6] it shows a high rate of spin with a projected rotational velocity of 54 km/s.^[7] The star has 2.2 times the mass of the Sun mass and is radiating 57.5^[4] times the Sun's luminosity from its photosphere at an effective temperature of 7,505 K.^[4]

The companion star was first reported by S. W. Burnham in 1872.^[9] Designated η Canis Minoris B, it is an eleventh-magnitude star located at an angular separation of 4 arcseconds from the primary. At the distance of this system, this is equivalent to a physical separation of around 440 AU from the main star, taking around 5,000 years to orbit it.^[10]