Gamma Arietis
 Location of γ Arietis (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Aries |
| Right ascension | 01h 53m 31.81479s[1] |
| Declination | +19° 17′ 37.8790″[1] |
| Apparent magnitude (V) | 3.86 (4.58/4.64)[2] |
| Characteristics | |
| Spectral type | B9 V + A1p Si[2] |
| U−B color index | –0.12[3] |
| B−V color index | –0.04[3] |
| Astrometry | |
| Radial velocity (Rv) | +3.7[4] km/s |
| Proper motion (μ) | RA: +79.20[1] mas/yr Dec.: –97.63[1] mas/yr |
| Parallax (π) | 19.88 ± 0.96[1] mas |
| Distance | 164 ± 8 ly (50 ± 2 pc) |
| Details | |
| Gam1 Ari | |
| Radius | 1.9[5] R☉ |
| Rotational velocity (v sin i) | 54[6] km/s |
| Gam2 Ari | |
| Surface gravity (log g) | 4.25[7] cgs |
| Temperature | 10,970[7] K |
| Metallicity [Fe/H] | 0.43 ± 0.14[8] dex |
| Rotational velocity (v sin i) | 201[6] km/s |
| Other designations | |
| Gam1 Ari: HD 11502, HR 545, SAO 92680. | |
| Gam2 Ari: HD 11503, HR 546, SAO 92681. | |
Gamma Arietis (γ Ari, γ Arietis) is the Bayer designation for a binary star system in the northern constellation of Aries. It has the traditional name Mesarthim, which is of obscure origin.[10] The combined apparent visual magnitude of the two stars is 3.86,[2] 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 mas,[1] the distance to Gamma Arietis is approximately 164 light-years (50 parsecs).
The double star nature of this system was discovered by Robert Hooke in 1664.[11] The two components have an angular separation of 7.606 arcseconds,[2] which can be resolved with a small telescope. The orbital period of the pair is greater than 5000 years.[12] The brighter component, γ¹ Arietis, is a magnitude 4.58 B-type main sequence star with a stellar classification of B9 V.[2] The secondary, γ² Arietis, is a Lambda Boötis[7] (chemically peculiar) star with a stellar classification of A1p Si and a magnitude of 4.64.[2] 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.
In culture
It has the traditional name Mesarthim, of obscure origin, and has been called "the First Star in Aries" as having been at one time the nearest visible star to the equinoctial point. The name Mesarthim may be from the Hebrew word mᵋshārᵋtīm, meaning "the minister",[10] or the Arabic word Al Muthartim (ألمثرتم), meaning "the ram".[13] The meaning "servants" has also been suggested.[14] In Sanskrit, the Aeris is known as Mesha (The ram) and the First point of Aries is Meshadi. The name could have very well originated from this and transformed to Mesarthim.
In Chinese, 婁宿 (Lóusù), meaning Bond (asterism), refers to an asterism consisting of γ Arietis, β Arietis and α Arietis.[15] Consequently, α Arietis itself is known as 婁宿二 (Lóusù Èr, English: the Second Star of Bond.)[16]
In Hindu astrology, Beta Arietis (Sheratan) and Gamma Arieties (Mesartim) are Ashwinis, the twin gods who act as doctors of the divine of the world.(Richard H Allen)
References
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- ↑ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- ↑ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
