Alpha Muscae

Alpha Muscae

Template:Location mark Location of α Muscae (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Musca
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	+2.69
Characteristics
Spectral type	B2 IV–V
U−B Template:Engvar	−0.854
B−V Template:Engvar	−0.219
Variable type	β Cep
Astrometry
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	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	−2.2
Details
Mass	Template:Solar mass
Radius	Template:Solar radius calculatorTemplate:Efn Template:Solar radius
Luminosity	Template:Solar luminosity
Surface gravity (log g)	4.06 cgs
Temperature	20,400 K
Rotational velocity (v sin i)	114 km/s
Age	Myr
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
Template:Odlist
Database references
SIMBAD	data

Alpha Muscae, Latinized from α Muscae, 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 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 5.2 times the radius.Template:Efn 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, giving it the blue-white hue of a B-type star.

File:AlphaMusLightCurve.png

A light curve for Alpha Muscae, plotted from TESS data

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. 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. Alpha Muscae 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.