Gamma Arietis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aries |
| Right ascension | 01h 53m 31.813s |
| Declination | +19° 17′ 37.88″ |
| Apparent magnitude (V) | 3.86 (4.58/4.64) |
| Characteristics | |
| Gamma1 Ari (B) | |
| Spectral type | A0Vnp λ Boo or A0IV-V(n)kB8 |
| B−V color index | −0.14 |
| Gamma2 Ari (A) | |
| Spectral type | A2IVpSiSrCr |
| B−V color index | −0.03 |
| Variable type | α2 CVn |
| Astrometry | |
| Radial velocity (Rv) | +3.7 km/s |
| Proper motion (μ) | RA: +77.138 mas/yr Dec.: −97.321 mas/yr |
| Parallax (π) | 19.6268±0.1526 mas |
| Distance | 166 ± 1 ly (51.0 ± 0.4 pc) |
| Absolute magnitude (MV) | −0.10 |
| Details | |
| Gamma1 Ari (Ba) | |
| Mass | 2.67 M☉ |
| Radius | 1.97±0.12 R☉ |
| Luminosity | 42.0 L☉ |
| Surface gravity (log g) | 4.26 cgs |
| Temperature | 11,000±1,100 K |
| Rotational velocity (v sin i) | 54 km/s |
| Age | 34 Myr |
| Gamma2 Ari (A) | |
| Mass | 2.72 M☉ |
| Radius | 1.941 R☉ |
| Luminosity | 41.5 L☉ |
| Surface gravity (log g) | 4.30 cgs |
| Temperature | 10,512 K |
| Metallicity [Fe/H] | 0.43±0.14 dex |
| Rotational velocity (v sin i) | 201 km/s |
| Gamma1 Ari (Bb) | |
| Mass | 0.7 M☉ |
| Temperature | 4,312 K |
| Metallicity [Fe/H] | −0.5 dex |
| Rotational velocity (v sin i) | 5 km/s |
| Other designations | |
| 5 Ari, BD+18 243, HIP 8832, WDS J01535+1918 | |
| Gamma1 Ari (B): HD 11502, HR 545, SAO 92680, WDS J01535+1918B | |
| Gamma2 Ari (A): GC 2291, HD 11503, HR 546, SAO 92681, WDS J01535+1918A | |
| Database references | |
| SIMBAD | γ Ari |
| γ1 Ari (B) | |
| γ2 Ari (A) | |
Gamma Arietis is a binary or possibly trinary star system in the northern constellation of Aries. Its name is a Bayer designation that is Latinized from γ Arietis, and abbreviated Gamma Ari or γ Ari. This system is called "The First Star in Aries" as having been at one time the nearest visible star to the equinoctial point. The combined apparent visual magnitude of the stars is 3.86, which is readily visible to the naked eye and makes this the fourth-brightest member of Aries. Based upon parallax measurements, the distance to Gamma Arietis from the Sun is approximately 166 light-years (51 parsecs).
The two components are designated γ1 Arietis or Gamma Arietis B and γ2 Arietis or Gamma Arietis A. The latter is formally named Mesarthim, pronounced /mɛˈsɑːrθɪm/, the traditional name for the Gamma Arietis system. γ1 Arietis may itself be a spectroscopic binary with a low mass companion.