20 Monocerotis
Star in the constellation Monoceros
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20 Monocerotis is a single[9] star located about 194[1] light years away from the Sun in the equatorial constellation of Monoceros. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.92.[2] The star is receding from the Earth with a heliocentric radial velocity of +78 km/s.[5]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Monoceros |
| Right ascension | 07h 10m 13.68177s[1] |
| Declination | −04° 14′ 13.5829″[1] |
| Apparent magnitude (V) | 4.92[2] |
| Characteristics | |
| Evolutionary stage | horizontal branch[3] |
| Spectral type | K0III[4] |
| U−B color index | +0.78[2] |
| B−V color index | +1.03[2] |
| Astrometry | |
| Radial velocity (Rv) | +77.74[5] km/s |
| Proper motion (μ) | RA: −0.714[1] mas/yr Dec.: +217.298[1] mas/yr |
| Parallax (π) | 16.8419±0.1692 mas[1] |
| Distance | 194 ± 2 ly (59.4 ± 0.6 pc) |
| Absolute magnitude (MV) | 0.94[6] |
| Details[7] | |
| Mass | 1.07±0.20 M☉ |
| Radius | 10.25±0.11[1] R☉ |
| Luminosity | 46.36±0.56[1] L☉ |
| Surface gravity (log g) | 2.53±0.10 cgs |
| Temperature | 4,714±46 K |
| Metallicity [Fe/H] | −0.25±0.03 dex |
| Rotational velocity (v sin i) | 2.33±0.50 km/s |
| Age | 5.75±2.85 Gyr |
| Other designations | |
| 20 Mon, BD−04°1840, FK5 1186, GC 9477, HD 54810, HIP 34622, HR 2701, SAO 134282, CCDM J07102-0414A, WDS J07102-0414A[8] | |
| Database references | |
| SIMBAD | data |
This object is an aging giant star with a stellar classification of K0 III.[4] It is a red clump giant,[3] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star is around six[7] billion years old with 1.1 times the mass of the Sun. After exhausting the supply of hydrogen at its core, it has expanded to 10.3[1] times the Sun's radius. It is radiating 46[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,714 K.[7]
In addition to the primary, three visual companions have been reported: component B, with magnitude 12.93 and separation 67.8", C, with magnitude 10.16 and separation 167.9", and D, with magnitude 12.46 and separation 102.3".[10]