Beta Microscopii
Constellation Microscopium star
From Wikipedia, the free encyclopedia
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]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Microscopium |
| Right ascension | 20h 51m 58.7618s[1] |
| Declination | −33° 10′ 40.705″[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]