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 | |
| Evolutionary stage | main sequence[3] |
| Spectral type | B2 IV–V[4] |
| U−B color index | −0.854[2] |
| B−V color index | −0.219[2] |
| Variable type | β Cep[5] |
| Astrometry | |
| Radial velocity (Rv) | +13[6] 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[7] |
| Details | |
| Mass | 8.8±0.1[4] M☉ |
| Radius | 5.22 ± 0.06[8][a] R☉ |
| Luminosity | 4,270±100[8] L☉ |
| Surface gravity (log g) | 4.06[7] cgs |
| Temperature | 20,400[8] K |
| Rotational velocity (v sin i) | 114[9] km/s |
| Age | 18.3±3.2[4] Myr |
| Other designations | |
| α Mus, CD−68 1104, CPD−68 1702, FK5 474, HD 109668, HIP 61585, HR 4798, SAO 251974[10] | |
| Database references | |
| SIMBAD | data |
With a stellar classification of B2 IV-V,[4] 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[4] times the mass and 5.2 times the radius.[a] This star is radiating around 4,300 times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 20,400 K,[7] giving it the blue-white hue of a B-type star.[11]
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,[5] although Stankov and Handler (2005) listed it as a poor or rejected candidate in their Catalog of Galactic β Cephei Stars.[9] 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.[13] Alpha Muscae is rotating rapidly with a projected rotational velocity of 114 km s−1[9] and has an estimated age of about 18 million years.[4]
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.[7] 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.[4]
In the culture of the indigenous Wardaman people of Australia, this star has the name Burangalul, referring to the "forehead band" of the boomerang constellation Buran, which is equivalent to Musca.[14]
Notes
- Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K:
