Mu Persei

Mu Persei, Latinised from μ Persei, is a binary star system in the northern constellation of Perseus. It is visible to the naked eye as a point of light with a combined apparent visual magnitude of +4.16.^[2] The distance to this system is approximately 900 light-years based on parallax measurements.^[1] It is drifting further away with a radial velocity of +26 km/s.^[6]

Mu Persei

Location of μ Persei (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Perseus
Right ascension	04h 14m 53.86253s[1]
Declination	+48° 24′ 33.5912″[1]
Apparent magnitude (V)	+4.16[2]
Characteristics
Spectral type	G0Ib[3] + B9.5[4]
B−V color index	0.935±0.002[5]
Astrometry
Radial velocity (Rv)	26.46[6] km/s
Proper motion (μ)	RA: 5.52[1] mas/yr Dec.: −17.37[1] mas/yr
Parallax (π)	3.62±0.20 mas[1]
Distance	900 ± 50 ly (280 ± 20 pc)
Absolute magnitude (MV)	−3.08[5]
Orbit[7]
Period (P)	284 d
Semi-major axis (a)	18.8 ± 8.8 mas
Eccentricity (e)	0.062
Inclination (i)	74 ± 24°
Longitude of the node (Ω)	296 ± 18°
Periastron epoch (T)	2,420,062
Argument of periastron (ω) (secondary)	302°
Details
Radius	~53[8] R☉
Luminosity	~2030[8] L☉
Surface gravity (log g)	1.74[9] cgs
Temperature	5418[9] K
Metallicity [Fe/H]	0.09[9] dex
Rotational velocity (v sin i)	12[10] km/s
Other designations
Mu Per, μ Per, 51 Persei, NSV 1518, BD+48 1063, FK5 1117, GC 5099, HD 26630, HIP 19812, HR 1303, SAO 39404, PPM 46912, CCDM J04149+4824A, WDS J04149+4825A[11]
Database references
SIMBAD	data

Mu Persei is a spectroscopic binary with an orbital period of 284 days and an eccentricity of about 0.06.^[7] The primary component is a yellow G-type supergiant star. With an effective temperature of about 5,400 K and a radius of 53 solar radii, this star has the luminosity of about 2,030 times that of the Sun.^[8] The companion is a B-type star with a class of B9.5^[4]

Mu Persei is moving through the galaxy at a speed of 35.6 km/s relative to the Sun. Its projected galactic orbit carries it between 23,900 and 32,400 light-years from the center of the galaxy.^[12]

Mu Persei came closest to the Sun 5.6 million years ago when it had brightened to magnitude 3.25 from a distance of 600 light-years.^[12]

Naming

In Chinese, 天船 (Tiān Chuán), meaning Celestial Boat, refers to an asterism consisting of μ Persei, η Persei, γ Persei, α Persei, ψ Persei, δ Persei, 48 Persei and HD 27084. Consequently, μ Persei itself is known as 天船七 (Tiān Chuán qī, English: the Seventh Star of Celestial Boat).^[13]