Epsilon Microscopii
Star in the constellation Microscopium
From Wikipedia, the free encyclopedia
Epsilon Microscopii, also named Aerostaticus,[10] is a single,[11] white-hued star in the southern constellationof Microscopium. It is faintly visible to the naked eye with an apparent visual magnitude of 4.71.[1] The annual parallax shift of the star is 19.7054 mas[2] as measured from Earth, which yields a distance estimate of around 166 light years. It is moving further from the Sun with a radial velocity of +7 km/s.[5]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Microscopium[1] |
| Right ascension | 21h 17m 56.28399s[2] |
| Declination | −32° 10′ 21.1515″[2] |
| Apparent magnitude (V) | 4.71[1] |
| Characteristics | |
| Spectral type | A1V[3] |
| U−B color index | +0.02[4] |
| B−V color index | +0.06[4] |
| Astrometry | |
| Radial velocity (Rv) | +7.20[5] km/s |
| Proper motion (μ) | RA: +54.36[2] mas/yr Dec.: −23.29[2] mas/yr |
| Parallax (π) | 19.7054±0.5472 mas[6] |
| Distance | 166 ± 5 ly (51 ± 1 pc) |
| Absolute magnitude (MV) | 0.97[1] |
| Details | |
| Mass | 2.18[7] M☉ |
| Radius | 2.2[7] R☉ |
| Luminosity | 35.62[1] L☉ |
| Surface gravity (log g) | 4.37[8] cgs |
| Temperature | 9,126[8] K |
| Metallicity [Fe/H] | −0.01[9] dex |
| Rotational velocity (v sin i) | 127[3] km/s |
| Age | 525[8] Myr |
| Other designations | |
| Aerostaticus, ε Mic, CD−32°16498, CPD−32°6329, FK5 801, GC 29774, HD 202627, HIP 105140, HR 8135, SAO 212874 | |
| Database references | |
| SIMBAD | data |
This star has a stellar classification of A1 V,[3] indicating it is an A-type main-sequence star that is generating energy through hydrogen fusion at its core. The stellar spectrum displays an overabundance of silicon in the star's atmosphere,[12] but the abundance of iron is the same as in the Sun.[9] The star has 2.2 times the mass of the Sun and 2.2 times the Sun's radius.[7] It is around a half billion years old[8] and is spinning rapidly with a projected rotational velocity of 127 km/s.[3] Epsilon Microscopii is radiating about 36 times the Sun's luminosity[1] from its photosphere at an effective temperature of 9,126 K.[8]
Epsilon Microscopii, Latinized from ε Microscopii, is the star's Bayer designation. It also had the Flamsteed designation 4 Piscis Austrini, assigned before the constellation Microscopium was invented by Lacaille.[13]
This star was the brightest star in the obsolete constellation Globus Aerostaticus, the hot air balloon, with Johann Elert Bode designating it with the Latin letter a.[14] The IAU Working Group on Star Names adopted the name Aerostaticus for this star on 16 July 2026, after the obsolete constellation.[10]