Alpha Muscae
Brightest star in Musca, a Beta Cephei variable.
Alpha Muscae, Latinized from α Muscae, is the brightest star in the southern circumpolar constellation of Musca. With an apparent visual magnitude of +2.7, it lies about 315 light-years from Earth. It is a B-type star with a classification of B2 IV-V, indicating it is evolving away from the main sequence toward a subgiant stage as its core hydrogen supply becomes exhausted.
- Apparent magnitude
- +2.7
- Spectral type
- B2 IV-V
- Distance
- 315 ly
- Mass
- 9 solar masses
- Radius
- 5.2 solar radii
- Luminosity
- 4,300 solar luminosities
- Effective temperature
- 20,400 K
Lore & Background
Alpha Muscae is a Beta Cephei variable star, though its classification has been disputed. A high-resolution spectroscopy study reported regular pulsations in its spectrum, confirming it as a Beta Cephei with high confidence, but an earlier catalog listed it as a poor or rejected candidate. The International Variable Star Index lists it as a Beta Cephei variable that varies in brightness from magnitude 2.68 to 2.73 with a period of 2.17 hours. The star rotates rapidly, with a projected rotational velocity noted in the literature, and has an estimated age of about 18 million years. It 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. Its peculiar velocity of 10 km/s is high but not enough to classify it as a runaway star.
Reader's Guide
Alpha Muscae holds significance as the brightest star in the faint constellation Musca, serving as a key reference point in the southern sky. Its status as a Beta Cephei variable, despite some catalog uncertainty, makes it an important object for studying stellar pulsations in massive stars. The star's membership in the Lower Centaurus–Crux sub-group of the Scorpius–Centaurus OB association places it within the nearest region of co-moving massive stars, offering insights into the dynamics and evolution of young stellar groups. Its rapid rotation and age of about 18 million years provide constraints on the early evolution of B-type stars. The star also carries cultural significance, as the Wardaman people of Australia know it as Burangalul, referring to the forehead band of the boomerang constellation Buran, which corresponds to Musca. This dual astronomical and cultural legacy underscores its role both as a scientific object and as a marker in indigenous sky lore.
Did You Know?
- It has nearly nine times the mass and 5.2 times the radius of the Sun.
- In Wardaman culture, it is called Burangalul, meaning the forehead band of the boomerang constellation Buran.
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