Gamma Arietis
 Location of γ Arietis (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Aries |
| Right ascension | 01h 53m 31.81479s |
| Declination | +19° 17′ 37.8790″ |
| Apparent magnitude (V) | 3.86 (4.58/4.64) |
| Characteristics | |
| Spectral type | B9 V + A1p Si |
| U−B color index | –0.12 |
| B−V color index | –0.04 |
| Astrometry | |
| Radial velocity (Rv) | +3.7 km/s |
| Proper motion (μ) |
RA: +79.20 mas/yr Dec.: –97.63 mas/yr |
| Parallax (π) | 19.88 ± 0.96mas |
| Distance | 164 ± 8 ly (50 ± 2 pc) |
| Details | |
| Gam1 Ari | |
| Radius | 1.9 R☉ |
| Rotational velocity (v sin i) | 54 km/s |
| Gam2 Ari | |
| Surface gravity (log g) | 4.25 cgs |
| Temperature | 10,970 K |
| Metallicity [Fe/H] | 0.43 ± 0.14 dex |
| Rotational velocity (v sin i) | 201 km/s |
| Other designations | |
| Gam1 Ari: HD 11502, HR 545, SAO 92680. | |
| Gam2 Ari: HD 11503, HR 546, SAO 92681. | |
| Database references | |
| SIMBAD | γ Ari |
| γ1 Ari | |
| γ2 Ari | |
Gamma Arietis (γ Arietis, abbreviated Gamma Ari, γ Ari) is a binary star in the northern constellation of Aries. The two components are designated γ¹ Arietis and γ² Arietis, also named Mesarthim. The combined apparent visual magnitude of the two stars is 3.86, which is readily visible to the naked eye and makes this the fourth-brightest member of Aries. Based upon an annual parallax shift of 19.88 milliarcseconds, the distance to Gamma Arietis from the Sun is approximately 164 light-years (50 parsecs).
The double star nature of this system was discovered by Robert Hooke in 1664. The two components have an angular separation of 7.606 arcseconds, which can be resolved with a small telescope. The orbital period of the pair is greater than 5000 years. The brighter component, γ² Arietis, is a Lambda Boötis (chemically peculiar) star with a stellar classification of A1p Si and a magnitude of 4.64. It is classified as an α2 CVn type variable star and its brightness varies by 0.04 magnitudes with a period of 2.61 days. The secondary, γ¹ Arietis, is a magnitude 4.58 B-type main-sequence star with a stellar classification of B9 V.
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