Mu Arietis
Star system in the constellation Aries
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Mu Arietis is a multiple star system in the northern constellation of Aries. Its name is a Bayer designation that is Latinized from μ Arietis, and abbreviated Mu Ari or μ Ari. This system is approximately 431 light-years (132 parsecs) distant from Earth, give or take a 8 light-year margin of error, and has a combined apparent visual magnitude of 5.74.[3] According to the Bortle Dark-Sky Scale, this means it is faintly visible to the naked eye from dark suburban skies. The system is positioned near the ecliptic and is subject to lunar occultation.[7]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aries[1] |
| Right ascension | 02h 42m 21.936s[2] |
| Declination | +20° 00′ 41.28″[2] |
| Apparent magnitude (V) | 5.74[3] (6.38/8.38/6.72/12.2)[4] |
| Characteristics | |
| Spectral type | A0 Vp + F2 V + A1 V[4] |
| U−B color index | −0.03[5] |
| B−V color index | −0.02[5] |
| Astrometry | |
| Radial velocity (Rv) | −6.0[6] km/s |
| Proper motion (μ) | RA: +29.086 mas/yr[2] Dec.: −46.133 mas/yr[2] |
| Parallax (π) | 7.5702±0.1425 mas[2] |
| Distance | 431 ± 8 ly (132 ± 2 pc) |
| Absolute magnitude (MV) | +0.41[1] |
| Orbit[7] | |
| Period (P) | 8.845±0.046 yr |
| Semi-major axis (a) | 0.0563±0.0008″ |
| Eccentricity (e) | 0.337±0.023 |
| Inclination (i) | 71.2±1.1° |
| Longitude of the node (Ω) | 101.0±1.0° |
| Periastron epoch (T) | B 1981.099±0.063 |
| Argument of periastron (ω) (secondary) | 92.3±1.7° |
| Details | |
| μ Ari Aa | |
| Mass | 3.4±1.7[7] M☉ |
| Luminosity | 71.7[1] L☉ |
| Rotational velocity (v sin i) | 175[8] km/s |
| μ Ari Ab | |
| Mass | 2.1±1.7[7] M☉ |
| Other designations | |
| μ Ari, 34 Arietis, BD+19 403, GC 3256, HD 16811, HIP 12640, HR 793, SAO 93062, PPM 91916, WDS J02424+2001[9] | |
| Database references | |
| SIMBAD | data |
At the heart of this system is a close orbiting pair, designated μ Ari Aa, consisting of a magnitude 6.38 A-type main sequence star with a stellar classification of A0 Vp, and a magnitude 8.38 F-type main sequence companion with a classification of F2 V. These two components have an angular separation of 0.04 arcseconds. A third component, designated μ Ari Ab, consists of a magnitude 6.72 star with a classification of A1 V, orbiting the inner pair with a period of 8.845 years and an eccentricity of 0.34.[4] The orbit of this star has been measured using lunar occultations.[7] A smaller fourth component, μ Ari B, at an angular separation of 19.1 arcseconds, has a magnitude of 12.2.[4]
According to R. H. Allen's Star Names, μ Ari together with the stars of Musca Borealis (33 Ari, 35 Ari, 39 Ari, and 41 Ari) formed the Coptic asterism Koleōn, "the Belly, or Scabbard".[10] A 1971 NASA catalog of star names listed μ Ari with the name Koleon.[11]