![cover image](https://wikiwandv2-19431.kxcdn.com/_next/image?url=https://upload.wikimedia.org/wikipedia/commons/thumb/d/dc/Musca_IAU.svg/640px-Musca_IAU.svg.png&w=640&q=50)
Alpha Muscae
Star in the constellation Musca / From Wikipedia, the free encyclopedia
Alpha Muscae, Latinized from α Muscae, is a star in the southern circumpolar constellation of Musca. With an apparent visual magnitude of +2.7,[2] 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.[1]
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Musca |
Right ascension | 12h 37m 11.01789s[1] |
Declination | –69° 08′ 08.0332″[1] |
Apparent magnitude (V) | +2.69[2] |
Characteristics | |
Spectral type | B2 IV–V[3] |
U−B color index | −0.854[2] |
B−V color index | −0.219[2] |
Variable type | β Cep[4] |
Astrometry | |
Radial velocity (Rv) | +13[5] km/s |
Proper motion (μ) | RA: −40.20[1] mas/yr Dec.: −12.80[1] mas/yr |
Parallax (π) | 10.34 ± 0.11 mas[1] |
Distance | 315 ± 3 ly (97 ± 1 pc) |
Absolute magnitude (MV) | –2.2[6] |
Details | |
Mass | 8.8±0.1[3] M☉ |
Radius | 4.8[7] R☉ |
Luminosity | 4,000[6] L☉ |
Surface gravity (log g) | 4.06[6] cgs |
Temperature | 21,400[6] K |
Rotational velocity (v sin i) | 114[8] km/s |
Age | 18.3±3.2[3] Myr |
Other designations | |
Database references | |
SIMBAD | data |
With a stellar classification of B2 IV-V,[3] 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[3] times the mass and almost five[7] times the radius. This star is radiating around 4,000[6] times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 21,400 K,[6] giving it the blue-white hue of a B-type star.[10]
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/AlphaMusLightCurve.png/640px-AlphaMusLightCurve.png)
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,[4] although Stankov and Handler (2005) listed it as a poor or rejected candidate in their Catalog of Galactic β Cephei Stars.[8] The International Variable Star Index lists it as a Beta Cephei variable which varies in brightness from magnitude 2.68 to 2.73, with a period of 2.17 hours.[12] Alpha Muscae is rotating rapidly with a projected rotational velocity of 114 km s−1[8] and has an estimated age of about 18 million years.[3]
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.[6] 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.[3]