Beta Microscopii

Beta Microscopii (Beta Mic), Latinized from β Microscopii, is a solitary star in the constellation Microscopium. It is close to the lower limit of stars that are visible to the naked eye having an apparent visual magnitude of 6.05^[2] Based upon an annual parallax shift of 6.5022 mas as seen from Earth,^[1] this star is located 502 light years away^[1] from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.19 due to interstellar dust.^[11]

β Microscopii

Location of β Microscopii (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Microscopium
Right ascension	20h 51m 58.7618s[1]
Declination	−33° 10′ 40.7051″[1]
Apparent magnitude (V)	6.05±0.01[2]
Characteristics
Spectral type	A1 IV[3]
B−V color index	+0.03[4]
Astrometry
Radial velocity (Rv)	−12±4.3[5] km/s
Proper motion (μ)	RA: +7.712 mas/yr[1] Dec.: −5.568 mas/yr[1]
Parallax (π)	6.5022±0.0451 mas[1]
Distance	502 ± 3 ly (154 ± 1 pc)
Absolute magnitude (MV)	+0.22[6]
Details
Mass	2.96[7] M☉
Radius	3.5±0.1[8] R☉
Luminosity	77.25[6] L☉
Surface gravity (log g)	3.58[9] cgs
Temperature	8,942[10] K
Metallicity [Fe/H]	0.00[11] dex
Rotational velocity (v sin i)	275±3[12] km/s
Age	337[11] Myr
Other designations
β Mic, 32 Microscopii[13], CD−33° 15245, HD 198529, HIP 102989, HR 7979, SAO 212499[14]
Database references
SIMBAD	data

Beta Mic has a stellar classification of A1 IV,^[3] indicating that it is an evolved A-type subgiant. Older sources give it a class of A2 Vn,^[15] suggesting that it is an A-type main-sequence star with nebulous absorption lines due to rapid rotation. Consistent with the older classification, the star is spinning rapidly with a projected rotational velocity of 275 km/s.^[12] The star has 2.96 times the mass of the Sun^[7] and due to its evolved status, has a radius of 3.5 R_☉.^[8] It radiates at 77.2 times the luminosity of the Sun^[6] from its photosphere at an effective temperature of 8,942 K,^[10] giving a white hue. Beta Mic has a solar metallicity and is estimated to be around 340 million years old.^[11]