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 | M0Ve[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) | 253.41 ± 0.80[5] mas |
| Distance | 12.87 ± 0.04 ly (3.95 ± 0.01 pc) |
| Absolute magnitude (MV) | 8.69[2] |
| Details | |
| Mass | 0.60[2] M☉ |
| Radius | 0.51[6] R☉ |
| Luminosity (bolometric) | 0.072[7] L☉ |
| Luminosity (visual, LV) | 0.029 L☉ |
| Surface gravity (log g) | 4.78[6] cgs |
| Temperature | 3,800[8] K |
| Metallicity [Fe/H] | -0.62 ± 0.07[9] dex |
| Rotation | 40 ± 12 days[10] |
| Rotational velocity (v sin i) | 3.3[4] km/s |
| Age | < 0.40[6] 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. Although it is generally 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. At an apparent magnitude of +6.7, it may only be visible to the unaided eye under exceptionally good viewing conditions, under dark skies. 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.[11]
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,[12] 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.[13] Its closest approach to the Sun occurred about 20,000 years ago when it came within 12 light-years (3.7 parsecs).[14] Due to its low mass (60% of the Sun), it has an expected lifespan of about 7.5 × 1010 years,[15] seven times longer than the Sun's.
Despite efforts by astronomers, as of 2011 no planets have been detected in orbit around this star.[16]
Lacaille 8760 is one of the largest and brightest red dwarfs known, with about 60% the mass and 51% the radius of the Sun.
See also
References
- 1 2 3 4 Perryman, M. A. C.; et al. (July 1997), "The HIPPARCOS Catalogue", Astronomy and Astrophysics, 323: L49–L52, Bibcode:1997A&A...323L..49P.
- 1 2 3 "The One Hundred Nearest Star Systems", RECONS, Georgia State University, retrieved 2015-06-25.
- 1 2 3 4 "V* AX Mic -- Flare Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2011-02-18.
- 1 2 3 Torres, C. A. O.; et al. (December 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. See the online data. - ↑ Perryman; et al. (1997). "HIP 105090". The Hipparcos and Tycho Catalogues. Retrieved 2014-10-21.
- 1 2 3 Takeda, Genya; et al. (February 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.
- ↑ Moro-Martín, A.; et al. (March 2015). "Does the Presence of Planets Affect the Frequency and Properties of Extrasolar Kuiper Belts? Results from the Herschel Debris and Dunes Surveys". The Astrophysical Journal. 801 (2): 28. arXiv:1501.03813. Bibcode:2015ApJ...801..143M. doi:10.1088/0004-637X/801/2/143.Vizier catalog entry
- ↑ Gautier, Thomas N., III; et al. (September 2007), "Far-Infrared Properties of M Dwarfs", The Astrophysical Journal, 667 (1): 527–536, arXiv:0707.0464, Bibcode:2007ApJ...667..527G, doi:10.1086/520667.
- ↑ Koleva, M.; Vazdekis, A. (February 2012). "Stellar population models in the UV. I. Characterisation of the New Generation Stellar Library". Astronomy & Astrophysics. 538: A143. arXiv:1111.5449. Bibcode:2012A&A...538A.143K. doi:10.1051/0004-6361/201118065. VizieR catalog entry
- ↑ Byrne, P. B.; Doyle, J. G. (January 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.
- ↑ Croswell, Ken (July 2003), "The Brightest Red Dwarf", Sky & Telescope: 32, retrieved 2011-02-18.
- ↑ Byrne, P. B. (April 1981), "Gliese 825 - A new flare star", Monthly Notices of the Royal Astronomical Society, 195: 143–147, Bibcode:1981MNRAS.195..143B, doi:10.1093/mnras/195.2.143.
- ↑ Allen, C.; Herrera, M. A. (April 1998), "The Galactic Orbits of Nearby UV Ceti Stars", Revista Mexicana de Astronomia y Astrofisica, 34: 37–46, Bibcode:1998RMxAA..34...37A.
- ↑ 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. (December 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.
- ↑ Carson, J. C.; et al. (December 2011), "Low-mass evolution - Zero-age main sequence to asymptotic giant branch", The Astrophysical Journal, 743 (2): 141, arXiv:1110.2191, Bibcode:2011ApJ...743..141C, doi:10.1088/0004-637X/743/2/141.
- Odert, P.; et al. (2008), "Habitability of M-type Stars - a Catalogue of Nearby M Dwarfs", Central European Astrophysical Bulletin, 32: 149–156, Bibcode:2008CEAB...32..149O.