Epsilon Monocerotis
| Observation data Epoch J2000 Equinox | |
|---|---|
| Constellation | Monoceros |
| ε Mon A | |
| Right ascension | 06h 23m 46.08471s |
| Declination | 4° 35′ 34.3153″ |
| Apparent magnitude (V) | 4.39 |
| ε Mon B | |
| Right ascension | 06h 23m 46.48292s |
| Declination | 4° 35′ 45.2307″ |
| Apparent magnitude (V) | 6.72 |
| Characteristics | |
| ε Mon A | |
| Spectral type | A5 IV |
| U−B color index | +0.14 |
| B−V color index | +0.20 |
| ε Mon B | |
| Spectral type | F5 V |
| U−B color index | −0.05 |
| B−V color index | +0.45 |
| Astrometry | |
| ε Mon A | |
| Radial velocity (Rv) | +13.10 km/s |
| Proper motion (μ) | RA: −22.06 mas/yr Dec.: +10.91 mas/yr |
| Parallax (π) | 26.67±0.90 mas |
| Distance | 122 ± 4 ly (37 ± 1 pc) |
| Absolute magnitude (MV) | 1.52 |
| ε Mon B | |
| Radial velocity (Rv) | +12.40 km/s |
| Proper motion (μ) | RA: −21.86 mas/yr Dec.: +11.35 mas/yr |
| Parallax (π) | 26.95 ± 0.99 mas |
| Distance | 121 ± 4 ly (37 ± 1 pc) |
| Absolute magnitude (MV) | +3.88 |
| Details | |
| ε Mon A | |
| Mass | 2.04 M☉ |
| Radius | 2.5 R☉ |
| Luminosity | 25 L☉ |
| Surface gravity (log g) | 3.95 cgs |
| Temperature | 7,923 K |
| Metallicity [Fe/H] | −0.11 dex |
| Rotational velocity (v sin i) | 149 km/s |
| ε Mon B | |
| Mass | 1.16 M☉ |
| Radius | 1.1 R☉ |
| Luminosity | 2.39 L☉ |
| Surface gravity (log g) | 3.95 cgs |
| Temperature | 7,923 K |
| Rotational velocity (v sin i) | 25 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 | data |
| SIMBAD | data |
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.
The white-hued primary component has a stellar classification of A5 IV, suggesting it is an aging subgiant star. Its apparent magnitude is 4.39 and it is approximately 122 light years away based on parallax. It is reportedly a spectroscopic binary with a period around 331 days.
The B component, at a separation of around 12.3", is a yellow-white hued F-type main-sequence star of class F5 V and an apparent magnitude of 6.72.