Beta Muscae

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Beta Muscae
Diagram showing star positions and boundaries of the Musca constellation and its surroundings
Cercle rouge 100%.svg

Location of β Musca (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Musca
Right ascension 12h 46m 16.80410s[1]
Declination –68° 06′ 29.2164″[1]
Apparent magnitude (V) 3.05 (3.51 + 4.01)[2]
Spectral type B2 V + B3 V[2]
U−B color index –0.766[3]
B−V color index –0.198[3]
Radial velocity (Rv) +42[4] km/s
Proper motion (μ) RA: –41.97[1] mas/yr
Dec.: –8.89[1] mas/yr
Parallax (π) 9.55 ± 0.41[1] mas
Distance 340 ± 10 ly
(105 ± 4 pc)
Period (P) 194.28 yr
Semi-major axis (a) 0.969"
Eccentricity (e) 0.598
Inclination (i) 37.1°
Longitude of the node (Ω) 349.4°
Periastron epoch (T) 1857.50
Argument of periastron (ω)
β Mus A
Mass 7.35[6] M
Age 15.1 ± 1.2[7] Myr
β Mus B
Mass 6.40[6] M
Other designations
bet Mus, CPD-67 2064, HD 110879, HIP 62322, HR 4844, SAO 252019.[8]

Beta Muscae (β Muscae, β Mus) is a binary star in the southern circumpolar constellation of Musca. With a combined apparent visual magnitude of 3.07,[2] it is the second brightest star (or star system) in the constellation. Judging by the parallax results, it is located at a distance of roughly 330–350 light-years (100–110 parsecs) from the Earth.[1]

This is a binary star system with a period of about 194 years at an orbital eccentricity of 0.6.[5] As of 2007, the two stars had an angular separation of 1.206 arcseconds at a position angle of 35°.[6] The components are main sequence stars of similar size and appearance. The primary component, β Muscae A, has an apparent magnitude of 3.51, a stellar classification of B2 V,[2] and about 7.35 times the Sun's mass.[6] The secondary component, β Muscae B, has an apparent magnitude of 4.01, a stellar classification of B3 V,[2] and is about 6.40 times the mass of the Sun.[6]

This is a confirmed member of the Scorpius-Centaurus Association,[2][6] which is a group of stars with similar ages, locations, and trajectories through space, implying that they formed together in the same molecular cloud. Beta Muscae is considered a runaway star system as it has a high peculiar velocity of 43.9 km s−1 relative to the normal galactic rotation. Runaway stars can be produced through several means, such as through an encounter with another binary star system. Binary systems form a relatively small fraction of the total population of runaway stars.[9]


  1. ^ a b c d e f 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 c d e f 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 
  3. ^ a b Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A Photometric Investigation of the Scorpio-Centaurus Association", Astrophysical Journal Supplement 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168 
  4. ^ Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953QB901.W495..... 
  5. ^ a b "Sixth Catalog of Orbits of Visual Binary Stars", U.S. Naval Observatory, retrieved 2008-06-22 
  6. ^ a b c d e f Kouwenhoven, M. B. N.; Brown, A. G. A.; Portegies Zwart, S. F.; Kaper, L. (October 2007), "The primordial binary population. II. Recovering the binary population for intermediate mass stars in Scorpius OB2", Astronomy and Astrophysics 474 (1): 77–104, arXiv:0707.2746, Bibcode:2007A&A...474...77K, doi:10.1051/0004-6361:20077719 
  7. ^ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x 
  8. ^ "CCDM J12463-6806AB -- Double or multiple star", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2012-01-20 
  9. ^ Hoogerwerf, R.; de Bruijne, J. H. J.; de Zeeuw, P. T. (January 2001), "On the origin of the O and B-type stars with high velocities. II. Runaway stars and pulsars ejected from the nearby young stellar groups", Astronomy and Astrophysics 365: 49–77, arXiv:astro-ph/0010057, Bibcode:2001A&A...365...49H, doi:10.1051/0004-6361:20000014 

External links[edit]

  • Kaler, James B., "Beta Muscae", Stars (University of Illinois), retrieved 2012-01-20