Lacaille 8760

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Lacaille 8760
Observation data
Epoch J2000
Constellation
(pronunciation)		 Microscopium
Right ascension 21h 17m 15.3s
Declination -38° 52' 02"
Apparent magnitude (V) 6.67
Characteristics
Spectral type M2 Ve
U-B color index 1.19
B-V color index 1.41
Variable type Flare star
Astrometry
Radial velocity (Rv) +24.1 km/s
Proper motion (μ) RA: -3259.00 mas/yr
Dec.: -1146.99 mas/yr
Parallax (π) 253.43 ± 1.12 mas
Distance 12.87 ± 0.06 ly
(3.95 ± 0.02 pc)
Absolute magnitude (MV) 8.69
Details
Mass 0.60 M☉
Radius 0.66 R☉
Luminosity 0.028 L☉
Temperature 3,340 K
Metallicity >50% Sun
Rotation ?
Age >4.6 × 109 years
Other designations
AX Microscopii, GJ 825, HD 202560, LHS 66, CD-39°14192, GCTP 5117, HIP 105090.

Lacaille 8760 is a red dwarf star in the constellation Microscopium, the microscope. Although it is slightly too faint to be seen without a telescope, this star is one of the nearest to our Sun at about 12.9 light years distance. This star was originally listed in a 1763 catalog that was published posthumously by the French Abbé Nicolas Louis de Lacaille. He observed this star in the southern sky while working from an observatory at the Cape of Good Hope.

In the past this star has been classified anywhere from spectral class K7 down to M2. In 1979 the Irish astronomer Patrick Byrne discovered that this is a flare star, and it was given the variable star designation AX Microscopii. As a flare star it is relatively quiet, only erupting on average less than once per day.

This star orbits around the galaxy in an elliptical orbit with a relatively high ellipticity of 0.23. Its closest approach to the Sun occurred about 20,000 years ago. Due to its low mass, this star has an expected lifespan of about 7 × 1010 years, far more than our own Sun.

Despite efforts by astronomers, thus far no planets have been detected in orbit around this star.

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