Eta Canis Minoris
Binary star system in the constellation Canis Minor
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Eta Canis Minoris is a binary star[2] 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,[4] which indicates it is faintly visible to the naked eye. Based on parallax measurements,[1] the distance to this system is approximately 318 light-years (97 pc) from the Sun. It is drifting further away with a line of sight velocity of +17 km/s.[5]
 | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Canis Minor |
| A | |
| Right ascension | 07h 28m 02.075s[1] |
| Declination | +06° 56′ 31.09″[1] |
| Apparent magnitude (V) | 11.1[2] |
| B | |
| Right ascension | 07h 28m 02.210s[3] |
| Declination | +06° 56′ 34.88″[3] |
| Apparent magnitude (V) | 11.1[2] |
| Characteristics | |
| Spectral type | F0 III[2] |
| U−B color index | +0.17[4] |
| B−V color index | +0.22[4] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | +17.2[5] 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[6] |
| B | |
| Proper motion (μ) | RA: −1.915 mas/yr[3] Dec.: −44.581 mas/yr[3] |
| Parallax (π) | 10.2562±0.0271 mas[3] |
| Distance | 318.0 ± 0.8 ly (97.5 ± 0.3 pc) |
| Details | |
| η CMi A | |
| Mass | 2.16[5] M☉ |
| Radius | 3.6[a] R☉ |
| Luminosity | 57.5[5] L☉ |
| Surface gravity (log g) | 3.66[7] cgs |
| Temperature | 7,505±66[5] K |
| Rotational velocity (v sin i) | 54[8] km/s |
| Age | 818[7] 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[9] | |
| Database references | |
| SIMBAD | data |
| B | |
The primary component, η Canis Minoris A, is a yellow-white F-type giant with a stellar classification of F0 III.[2] At the estimated age of 818 million years,[7] it shows a high rate of spin with a projected rotational velocity of 54 km/s.[8] The star has 2.2 times the mass of the Sun mass and is radiating 57.5[5] times the Sun's luminosity from its photosphere at an effective temperature of 7,505 K.[5]
The companion star was first reported by S. W. Burnham in 1872.[10] 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.[11]
Notes
- derived from known mass and surface gravity of star