Mu Arietis

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μ Arietis
Aries constellation map.svg
Red circle.svg
Location of μ Arietis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aries
Right ascension  02h 42m 21.93980s[1]
Declination +20° 00′ 41.2612″[1]
Apparent magnitude (V) 5.74[2] (6.38/8.38/6.72/12.2)[3]
Spectral type A0 Vp + F2 V + A1 V[3]
U−B color index –0.03[4]
B−V color index –0.02[4]
Radial velocity (Rv)–6.0[5] km/s
Proper motion (μ) RA: +27.68[1] mas/yr
Dec.: –47.64[1] mas/yr
Parallax (π)9.64 ± 0.88[1] mas
Distance340 ± 30 ly
(104 ± 9 pc)
Absolute magnitude (MV)+0.41[6]
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)
92.3 ± 1.7°
Mass3.4 ± 1.7 (Aa) / 2.1 ± 1.7 (Ab)[7] M
Luminosity71.7[6] L
Rotational velocity (v sin i)175[8] km/s
Other designations
μ Ari, 34 Arietis, BD+19 403, HD 16811, HIP 12640, HR 793, SAO 93062.[9]
Database references

Mu Arietis, Latinized from μ Arietis, is the Bayer designation for a star system in the northern constellation of Aries. It is approximately 340 light-years (100 parsecs) distant from Earth, give or take a 30 light-year margin of error, and has a combined apparent visual magnitude of 5.74.[2] According to the Bortle Dark-Sky Scale, this means it is faintly visible to the naked eye from dark suburban skies.

At the heart of this system is a close orbiting pair 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, consisting of a magnitude 6.72 star with a classification of A1 V, is orbiting the inner pair with a period of 8.845 years and an eccentricity of 0.34. A smaller fourth component, at an angular separation of 19.1 arcseconds, has a magnitude of 12.2.[3]


  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ^ a b Oja, T. (August 1991). "UBV photometry of stars whose positions are accurately known. VI". Astronomy and Astrophysics Supplement Series. 89 (2): 415–419. Bibcode:1991A&AS...89..415O.
  3. ^ a b c Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  4. ^ a b Osawa, K.; Hata, S. (1960), "Three colour photometry of B8-A2 stars.", Annals of the Tokyo Astronomical Observatory, 6: 148, Bibcode:1960AnTok...6..148O.
  5. ^ Palmer, D. R.; et al. (1968), "The radial velocities spectral types and projected rotational velocities of 633 bright northern A stars", Royal Observatory Bulletin, 135: 385, Bibcode:1968RGOB..135..385P.
  6. ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  7. ^ a b Mason, Brian D. (1997). "Binary Star Orbits from Speckle Interferometry. XI. Orbits of Twelve Lunar Occultation Systems". The Astronomical Journal. 114: 808. Bibcode:1997AJ....114..808M. doi:10.1086/118514.
  8. ^ Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
  9. ^ "mu. Ari". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-08-07.

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