Lacaille 8760
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Microscopium |
| Right ascension | 21h 17m 15.2697s[1] |
| Declination | −38° 52′ 02.502″[1] |
| Apparent magnitude (V) | 6.67[2] |
| Characteristics | |
| Spectral type | M0 Ve[3][4] |
| U−B color index | +1.165[3] |
| B−V color index | +1.395[3] |
| Variable type | Flare star |
| Astrometry | |
| Radial velocity (Rv) | +20.7[4] km/s |
| Proper motion (μ) | RA: -3258.79[1] mas/yr Dec.: -1146.51[1] mas/yr |
| Parallax (π) | 253.36 ± 1.13 mas[1] |
| Distance | 12.87 ± 0.06 ly (3.95 ± 0.02 pc) |
| Absolute magnitude (MV) | 8.69[2] |
| Details | |
| Mass | 0.60[2] M☉ |
| Radius | 0.51[5] R☉ |
| Surface gravity (log g) | 4.78[5] cgs |
| Temperature | 3,800[6] K |
| Rotation | 40 ± 12 days[7] |
| Rotational velocity (v sin i) | 3.3[4] km/s |
| Age | < 0.40[5] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| ARICNS | data |
Lacaille 8760 (AX Microscopii) is a red dwarf star in the constellation Microscopium, the microscope. Although it is slightly too faint to be seen without a telescope, it is one of the nearest stars to the Sun at about 12.9 light years distance. It 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.[8]
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,[9] 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.
Lacaille 8760 orbits around the galaxy with a relatively high ellipticity of 0.23.[10] Its closest approach to the Sun occurred about 20,000 years ago when it came within 12 ly (3.7 pc).[11] Due to its low mass (60 % of our Sun), it has an expected lifespan of about 7.5 × 1010 years,[12] 7 times more than for the Sun.
Despite efforts by astronomers, thus far no planets have been detected in orbit around this star.
Although Lacaille 8760 is the brightest red dwarf star visible in the night sky, it's still too dim to be seen with the naked eye. It is also one of the largest and brightest red dwarf stars known, with about 60% the mass and 51% the radius of the Sun.
See also
References
- ^ a b c d e Perryman, M. A. C.; et al. (1997), "The HIPPARCOS Catalogue", Astronomy and Astrophysics, 323: L49–L52, Bibcode:1997A&A...323L..49P
{{citation}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ a b c "The One Hundred Nearest Star Systems", RECONS, Georgia State University, retrieved 2011-02-18
- ^ a b c d "V* AX Mic -- Flare Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2011-02-18
- ^ a b c Torres, C. A. O.; et al. (2006), "Search for associations containing young stars (SACY). I. Sample and searching method", Astronomy and Astrophysics, 460 (3): 695–708, arXiv:astro-ph/0609258, Bibcode:2006A&A...460..695T, doi:10.1051/0004-6361:20065602
{{citation}}: Unknown parameter|month=ignored (help) See the online data. - ^ a b c Takeda, Genya; et al. (2007), "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog", The Astrophysical Journal Supplement Series, 168 (2): 297–318, arXiv:astro-ph/0607235, Bibcode:2007ApJS..168..297T, doi:10.1086/509763, retrieved 2011-08-26
{{citation}}: Unknown parameter|month=ignored (help) - ^ Gautier, Thomas N., III; et al. (2007), "Far-Infrared Properties of M Dwarfs", The Astrophysical Journal, 667 (1): 527–536, Bibcode:2007ApJ...667..527G, doi:10.1086/520667
{{citation}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Byrne, P. B.; Doyle, J. G. (1989), "Activity in late-type dwarfs. III - Chromospheric and transition region line fluxes for two dM stars", Astronomy and Astrophysics, 208 (1–2): 159–165, Bibcode:1989A&A...208..159B
{{citation}}: Unknown parameter|month=ignored (help) - ^ Croswell, Ken (2003), "The Brightest Red Dwarf", Sky & Telescope: 32, retrieved 2011-02-18
{{citation}}: Unknown parameter|month=ignored (help) - ^ Byrne, P. B. (1981), "Gliese 825 - A new flare star", Monthly Notices of the Royal Astronomical Society, 195: 143–147, Bibcode:1981MNRAS.195..143B
{{citation}}: Unknown parameter|month=ignored (help) - ^ Allen, C.; Herrera, M. A. (1998), "The Galactic Orbits of Nearby UV Ceti Stars", Revista Mexicana de Astronomia y Astrofisica, 34: 37–46, Bibcode:1998RMxAA..34...37A
{{citation}}: Unknown parameter|month=ignored (help) - ^ García-Sánchez, J.; et al. (2001), "Stellar encounters with the solar system", Astronomy and Astrophysics, 379: 634–659, Bibcode:2001A&A...379..634G, doi:10.1051/0004-6361:20011330
- ^ Despain, K. H. (1981), "Low-mass evolution - Zero-age main sequence to asymptotic giant branch", Astrophysical Journal, Part 1, 251: 639–653, Bibcode:1981ApJ...251..639D, doi:10.1086/159510
{{citation}}: Unknown parameter|month=ignored (help)
