Image of Lacaille 8760 (circled) in Bode's Uranographia (1801).[1] In the corresponding catalog this star is listed as № 36 in constellation Microscopium.[2]
AX Microscopii, AX Mic, CD−39°14192, GJ 825, HD 202560, HIP 105090, LHS 66[5]
Database references
SIMBAD
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Exoplanet Archive
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ARICNS
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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.[14] Number 8760 was assigned to this star in the 1847 edition of Lacaille's catalogue of 9,766 stars by Francis Baily.[15]
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,[16] and it was given the variable star designation AX Microscopii, or AX Mic. As a flare star it is relatively quiescent.
An ultraviolet band light curve for a flare on AX Microscopii, adapted from Byrne (1981)[16]
Lacaille 8760 is one of the largest and brightest red dwarfs known, with about 60%[4] the mass and 51%[8] the radius of the Sun. It is about five[13] billion years old and is spinning at a projected rotational velocity of 3.3 km/s,[6] giving it a rotation period of roughly 40 days.[12] The star is radiating 7.2%[9] of the luminosity of the Sun from its photosphere at an effective temperature of 3,800 K.[10]
Despite efforts by astronomers, as of 2011 no planets had been detected in orbit around this star.[17]
Lacaille 8760 orbits around the galaxy with a relatively high ellipticity of 0.23.[18] Its closest approach to the Sun occurred about 20,000 years ago when it came within 12 light-years (3.7 parsecs).[19] Due to its low mass (60% of the Sun), it has an expected lifespan of about 75 billion (7.5 × 1010) years,[20] seven times longer than the Sun's.
^e-rara.ch. Johann Elert Bode. Uranographia star atlas (1801), Tabula XVI
^Johann Elert Bode. Allgemeine Beschreibung und Nachweisung der Gestirne (1801), Page 67
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^Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
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^Francis Baily. A Catalogue of 9766 Stars (1847), Page 219
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Lacaille8760 (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'...
variables include Barnard's Star, Kapteyn's Star, 61 Cygni, Ross 248, Lacaille8760, Lalande 21185, Epsilon Eridani and Luyten 726-8. Ross 248 is the first...
First discovered Lacaille8760 1753 Originally listed in a 1763 catalog that was published posthumously by Abbé Nicolas Louis de Lacaille. First discovered...
near visual magnitude. The brightest red dwarf in Earth's night sky, Lacaille8760 (+6.7) is visible to the naked eye only under ideal viewing conditions...
temperatures; from 0.3 AU (just inside the orbit of Mercury) for a star like Lacaille8760, to as little as 0.032 AU for a star like Proxima Centauri (such a world...
exceptional conditions. The brightest-known M class main-sequence star is Lacaille8760, class M0V, with magnitude 6.7 (the limiting magnitude for typical naked-eye...
faint to be seen with the naked eye. AX Microscopii, better known as Lacaille8760, is a red dwarf which lies only 12.9 light-years from the Solar System...
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