Epsilon Muscae

Epsilon Muscae, Latinized as ε Muscae, is a red giant star of spectral type M5III in the constellation Musca.^[5] It is a 4th magnitude star, visible to the naked eye under good observing conditions. It is about 330 light-years from the Earth.^[2]

Epsilon Muscae

A light curve for Epsilon Muscae, plotted from Hipparcos data[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Musca
Right ascension	12h 17m 34.27564s[2]
Declination	−67° 57′ 38.65252″[2]
Apparent magnitude (V)	4.0 – 4.3[3]
Characteristics
Evolutionary stage	asymptotic giant branch[4]
Spectral type	M5 III[5]
Variable type	SRb[3]
Astrometry
Radial velocity (Rv)	7.1±0.7[citation needed] km/s
Proper motion (μ)	RA: −230.607±0.187 mas/yr[2] Dec.: −26.206±0.263 mas/yr[2]
Parallax (π)	9.9915±0.2 mas[2]
Distance	326 ± 7 ly (100 ± 2 pc)
Absolute magnitude (MV)	−0.77[6]
Details
Mass	2±0.3[7] M☉
Radius	116±9[7] R☉
Luminosity	1,738[2] L☉
Surface gravity (log g)	0.6±0.02[7] cgs
Temperature	3,470±125[7] K
Other designations
eps Mus, CPD−67 1931, HD 106849, HIP 59929, HR 4671, SAO 251830
Database references
SIMBAD	data

Originally a main-sequence star of around 2 solar masses,^[7] Epsilon Muscae is now on the asymptotic giant branch^[4] and has expanded to 117 times the Sun's diameter and 1,700 its luminosity.^[7] It is a semiregular variable, varying between visual magnitudes 4.0 and 4.3^[3] in eight distinct periods ranging from a month to over half a year in length.^[5] Its distance from the Earth is about the same as the Lower Centaurus–Crux subgroup of the Scorpius–Centaurus association, although it is moving much faster at around 100 km/s and does not share a common origin.^[8]