Gamma Monocerotis
Star in the constellation of Monoceros
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γ Monocerotis, Latinised as Gamma Monocerotis, is a binary star[9] system in the equatorial constellation of Monoceros. Based upon an annual parallax shift of 6.55 mas,[1] it is located roughly 500 light years from the Sun. It can be viewed with the naked eye, having an apparent visual magnitude of 3.96.[2] Gamma Monocerotis is moving away from the Sun with a radial velocity of −5 km/s.[4]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Monoceros |
| Right ascension | 06h 14m 51.33367s[1] |
| Declination | −06° 16′ 29.1880″[1] |
| Apparent magnitude (V) | 3.96[2] |
| Characteristics | |
| Spectral type | K1.5IIIBa0.3[3] |
| U−B color index | +1.42[2] |
| B−V color index | +1.31[2] |
| Astrometry | |
| Radial velocity (Rv) | −4.8±0.7[4] km/s |
| Proper motion (μ) | RA: −4.69[1] mas/yr Dec.: −19.30[1] mas/yr |
| Parallax (π) | 6.55±0.19 mas[1] |
| Distance | 500 ± 10 ly (153 ± 4 pc) |
| Absolute magnitude (MV) | -1.93[5] |
| Details[6] | |
| Mass | 4.09±0.14 M☉ |
| Radius | 50.8+1.5 −1.6 R☉ |
| Luminosity | 1,247±96 L☉ |
| Surface gravity (log g) | 1.61[7] cgs |
| Temperature | 4,810±66 K |
| Metallicity [Fe/H] | −0.15[7] dex |
| Rotational velocity (v sin i) | 4.0[8] km/s |
| Age | 170±20 Myr |
| Other designations | |
| γ Mon, 5 Monocerotis, BD−06°1469, FK5 2475, GC 7986, HD 43232, HIP 29651, HR 2227, SAO 133012, CCDM J06149-0616A, WDS J06149-0617A | |
| Database references | |
| SIMBAD | data |
This is an evolved K-type giant star with a stellar classification of K1.5 III Ba0.3.[3] The Ba0.3 suffix indicates this is a mild barium star, which means the spectrum displays abnormal abundance of s-process elements, including barium. These were deposited by an orbiting companion as it passed through the asymptotic giant branch stage. The companion is now a white dwarf star.[10]
It has reported companions B, at separation 53.7" and magnitude 13.1, and C, at separation 47.9" and magnitude 13.6.[11]