Alpha Muscae

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Alpha Muscae
Musca IAU.svg
Red circle.svg
Location of α Muscae (circled)
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 5.22 ± 0.06 [7] [a]   R
Luminosity 4,270±100 [7]   L
Surface gravity (log g)4.06 [6]   cgs
Temperature 20,400 [7]   K
Rotational velocity (v sin i)114 [8]  km/s
Age 18.3±3.2 [3]   Myr
Other designations
α Mus, CD 68 1104, CPD 68 1702, FK5  474, HD  109668, HIP  61585, HR  4798, SAO  251974 [9]
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, [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]

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 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, [6] giving it the blue-white hue of a B-type star. [10]

A light curve for Alpha Muscae, plotted from TESS data 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, [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]

Notes

  1. 1 2 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:

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