| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Microscopium |
| Right ascension | 21h 17m 15.26907s [3] |
| Declination | −38° 52′ 02.5039″ [3] |
| Apparent magnitude (V) | 6.67 [4] |
| Characteristics | |
| Spectral type | M0Ve [5] [6] |
| U−B color index | +1.165 [5] |
| B−V color index | +1.395 [5] |
| Variable type | Flare star |
| Astrometry | |
| Radial velocity (Rv) | +20.71±0.12 [3] km/s |
| Proper motion (μ) | RA: −3,258.966 mas/yr [3] Dec.: −1,145.862 mas/yr [3] |
| Parallax (π) | 251.9124 ± 0.0352 mas [3] |
| Distance | 12.947 ± 0.002 ly (3.9696 ± 0.0006 pc) |
| Absolute magnitude (MV) | 8.69 [4] |
| Details | |
| Mass | 0.60 [4] M☉ |
| Radius | 0.51 [7] R☉ |
| Luminosity (bolometric) | 0.072 [8] L☉ |
| Luminosity (visual, LV) | 0.029 L☉ |
| Surface gravity (log g) | 4.78 [7] cgs |
| Temperature | 3,800 [9] K |
| Metallicity [Fe/H] | −0.01±0.04 [10] dex |
| Rotational velocity (v sin i) | 3.3 [6] km/s |
| Age | 4.8±2.9 [11] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| ARICNS | data |
  Lacaille 8760 Location of Lacaille 8760 in the constellation Microscopium | |
Lacaille 8760 (AX Microscopii) is a red dwarf star in the constellation Microscopium. It is one of the nearest stars to the Sun at about 12.9 light-years' distance, and the brightest M-class main-sequence star in Earth's night sky, although it is generally too faint to be seen without a telescope. At an apparent magnitude of +6.7, it may only be visible to the unaided eye under exceptionally good viewing conditions, under dark skies.
This star was originally listed in a 1763 catalog that was published posthumously by the French Abbé Nicolas-Louis de Lacaille. He observed it in the southern sky while working from an observatory at the Cape of Good Hope. [12] Number 8760 was assigned to this star in the 1847 edition of Lacaille's catalogue of 9,766 stars by Francis Baily. [13]
In the past, Lacaille 8760 has been classified anywhere from spectral class K7 down to M2. In 1979, the Irish astronomer Patrick Byrne discovered that it is a flare star, [14] and it was given the variable star designation AX Microscopii, or AX Mic. As a flare star it is relatively quiescent.
Lacaille 8760 is one of the largest and brightest red dwarfs known, with about 60% [4] the mass and 51% [7] the radius of the Sun. It is about five [11] billion years old and is spinning at a projected rotational velocity of 3.3 km/s. [6] The star is radiating 7.2% [8] of the luminosity of the Sun from its photosphere at an effective temperature of 3,800 K. [9]
Despite efforts by astronomers, as of 2011 no planets had been detected in orbit around this star. [15]
Lacaille 8760 orbits around the galaxy with a relatively high ellipticity of 0.23. [16] Its closest approach to the Sun occurred about 20,000 years ago when it came within 12 light-years (3.7 parsecs ). [17] Due to its low mass (60% of the Sun), it has an expected lifespan of about 75 billion (7.5 × 1010) years, [18] seven times longer than the Sun's.
