Zeta1 Muscae

For other star systems with this Bayer designation see ζ Muscae

Zeta¹ Muscae, Latinized from ζ¹ Muscae and abbreviated ζ¹ Mus, is a suspected astrometric binary^[6] star system in the constellation Musca, located 2.6° west of Beta Muscae.^[7] It is bright enough to be visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.73,^[1] forming a visual pair with nearby Zeta² Muscae.^[7] The ζ¹ Mus system is around 417 light-years distant from the Sun, based on parallax, and is drifting further away with a radial velocity of +21 km/s.^[1]

Zeta¹ Muscae

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Musca[1]
Right ascension	12h 22m 12.02893s[2]
Declination	−68° 18′ 26.4093″[2]
Apparent magnitude (V)	5.73[1]
Characteristics
Evolutionary stage	Red-giant branch[2]
Spectral type	K0III[3]
B−V color index	+1.038±0.004[1]
Astrometry
Radial velocity (Rv)	+21.13±0.40[1] km/s
Proper motion (μ)	RA: −1.467[2] mas/yr Dec.: −47.437[2] mas/yr
Parallax (π)	9.1234±0.2059 mas[2]
Distance	357 ± 8 ly (110 ± 2 pc)
Absolute magnitude (MV)	0.73[1]
Details
Mass	2.80[2] M☉
Radius	12.1 or 14.1[2] R☉
Luminosity	82[2] L☉
Surface gravity (log g)	2.531[2] cgs
Temperature	5,000[2] K
Metallicity [Fe/H]	−0.21[4] dex
Rotational velocity (v sin i)	3.92[4] km/s
Age	456[2] Myr
Other designations
ζ1 Mus, CPD−67°1939, HD 107567, HIP 60329, HR 4704, SAO 251868[5]
Database references
SIMBAD	data

The suspected astrometric component of the ζ¹ Mus system was identified from acceleration behavior in the proper motion of the main star.^[8] The visible component is an aging giant star with a stellar classification of K0III;^[5] a star that has used up its core hydrogen and is cooling and expanding. It now has 12 or 14 times the radius of the Sun and is radiating 82 times the Sun's luminosity from its swollen photosphere at an effective temperature of 5,000 K.^[2]