Epsilon Monocerotis
Binary star system in the constellation Monoceros
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ε Monocerotis, Latinised as Epsilon Monocerotis, is the Bayer designation of a binary star system in the equatorial constellation Monoceros. Its location is a guide for sky navigation toward the Rosette Nebula.[13]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Monoceros |
| ε Mon A | |
| Right ascension | 06h 23m 46.08471s[1] |
| Declination | 4° 35′ 34.3153″[1] |
| Apparent magnitude (V) | 4.39[2] |
| ε Mon B | |
| Right ascension | 06h 23m 46.48292s[3] |
| Declination | 4° 35′ 45.2307″[3] |
| Apparent magnitude (V) | 6.72[4] |
| Characteristics | |
| ε Mon A | |
| Evolutionary stage | main sequence[5] |
| Spectral type | A5 IV[6] |
| U−B color index | +0.14[7] |
| B−V color index | +0.20[7] |
| ε Mon B | |
| Evolutionary stage | main sequence[3] |
| Spectral type | F5 V[6] |
| U−B color index | −0.05[8] |
| B−V color index | +0.45[8] |
| Astrometry | |
| ε Mon A | |
| Radial velocity (Rv) | +13.10[9] km/s |
| Proper motion (μ) | RA: −15.127[1] mas/yr Dec.: +7.701[1] mas/yr |
| Parallax (π) | 24.0777±0.2691 mas[1] |
| Distance | 135 ± 2 ly (41.5 ± 0.5 pc) |
| Absolute magnitude (MV) | 1.52[2] |
| ε Mon B | |
| Radial velocity (Rv) | +12.40[9] km/s |
| Proper motion (μ) | RA: −18.845[3] mas/yr Dec.: +0.658[3] mas/yr |
| Parallax (π) | 25.0633±0.0219 mas[3] |
| Distance | 130.1 ± 0.1 ly (39.90 ± 0.03 pc) |
| Absolute magnitude (MV) | +3.88[4] |
| Details | |
| ε Mon A | |
| Mass | 2.04[5] M☉ |
| Radius | 2.5[10] R☉ |
| Luminosity | 25[5] L☉ |
| Surface gravity (log g) | 3.95[11] cgs |
| Temperature | 7,923[11] K |
| Metallicity [Fe/H] | −0.11[12] dex |
| Rotational velocity (v sin i) | 149[5] km/s |
| ε Mon B | |
| Mass | 1.16[10] M☉ |
| Radius | 1.1[10] R☉ |
| Luminosity | 2.39[4] L☉ |
| Surface gravity (log g) | 3.95[11] cgs |
| Temperature | 7,923[11] K |
| Rotational velocity (v sin i) | 25[6] km/s |
| Other designations | |
| ε Mon, 8 Monocerotis, CCDM J06237+0436, WDS J06238+0436 | |
| ε Mon A: BD+04°1236, FK5 244, GC 8240, HD 44769, HIP 30419, HR 2298, SAO 113810 | |
| ε Mon B: BD+04°1237, FK5 244, GC 8241, HD 44770, HIP 30422, HR 2299, SAO 113811 | |
| Database references | |
| SIMBAD | A |
| B | |
The white-hued primary component has a stellar classification of A5 IV,[6] suggesting it is an aging subgiant star. Its apparent magnitude is 4.39[2] and it is approximately 135 light years away based on parallax. It is reportedly a spectroscopic binary with a period around 331 days.[14]
The B component, at a separation of around 12.3",[14] is a yellow-white hued F-type main-sequence star of class F5 V[6] and an apparent magnitude of 6.72.[4]