Epoch J2000.0 Equinox J2000.0
|Right ascension||12h 37m 11.01789s|
|Declination||–69° 08′ 08.0332″|
|Apparent magnitude (V)||+2.69|
|Spectral type||B2 IV–V|
|U−B color index||−0.854|
|B−V color index||−0.219|
|Variable type||β Cep|
|Radial velocity (Rv)||+13 km/s|
|Proper motion (μ)||RA: −40.20 mas/yr
Dec.: −12.80 mas/yr
|Parallax (π)||10.34 ± 0.11 mas|
|Distance||315 ± 3 ly
(97 ± 1 pc)
|Absolute magnitude (MV)||–2.2|
|Mass||8.8 ± 0.1 M☉|
|Surface gravity (log g)||4.06 cgs|
|Rotational velocity (v sin i)||114 km/s|
|Age||18.3 ± 3.2 Myr|
Alpha Muscae (α Muscae, α Mus) is a star in the southern circumpolar constellation of Musca. With an apparent visual magnitude of +2.7, it is the brightest star in the constellation. The distance to this star has been determined using parallax measurements, giving an estimate of about 315 light-years (97 parsecs) from Earth.
With a stellar classification of B2 IV-V, this star appears to be in the process of evolving away from the main sequence of stars like the Sun and turning a subgiant star, as the supply of hydrogen at its core becomes exhausted. It is larger than the Sun, with nearly nine times the mass and almost five times the radius. This star is radiating around 4,000 times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 21,400 K, giving it the blue-white hue of a B-type star.
Alpha Muscae appears to be a Beta Cephei variable star. Telting and colleagues report it as a Beta Cephei with a high degree of confidence as they found regular pulsations in its spectrum in a high-resolution spectroscopy study published in 2006, although Stankov and Handler (2005) listed it as a poor or rejected candidate in their Catalog of Galactic β Cephei Stars. It is rotating rapidly with a projected rotational velocity of 114 km s−1 and has an estimated age of about 18 million years.
This star is a proper motion member of the Lower-Centaurus Crux sub-group in the Scorpius-Centaurus OB association, the nearest such association of co-moving massive stars to the Sun. Alpha Muscae has a peculiar velocity of 10 km s−1, which, while high, is not enough for it to be considered a runaway star.
- van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
- 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
- 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:, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x
- Telting, J. H.; et al. (June 2006), "A high-resolution spectroscopy survey of β Cephei pulsations in bright stars", Astronomy and Astrophysics, 452 (3): 945–953, Bibcode:2006A&A...452..945T, doi:10.1051/0004-6361:20054730
- Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick, eds., The Revision of the General Catalogue of Radial Velocities, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E
- de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", Astronomy and Astrophysics, 216 (1-2): 44–61, Bibcode:1989A&A...216...44D
- Underhill, A. B.; et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society, 189: 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601
- Stankov, Anamarija; Handler, Gerald (June 2005), "Catalog of Galactic β Cephei Stars", The Astrophysical Journal Supplement Series, 158 (2): 193–216, arXiv:, Bibcode:2005ApJS..158..193S, doi:10.1086/429408
- "HD 109668 -- Variable Star of Beta Cep type", SIMBAD Astronomical Database, retrieved 2007-01-29
- "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16