Lacaille 8760

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Star
Lacaille 8760
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation microscope
Right ascension 21 h 17 m 15.27 s
declination -38 ° 52 ′ 2.5 ″
Apparent brightness 6.67 likes
Typing
B − V color index +1.41 
Spectral class M0 Ve
Variable star type UV 
Astrometry
Radial velocity (20.56 ± 0.13) km / s
parallax 251.83 ± 0.06  mas
distance 12.94 ± 0.01  ly
3.971 ± 0.001  pc
Visual absolute brightness M vis 8.69 likes
Proper movement 
Rec. Share: −3258.55 ± 0.10  mas / a
Dec. portion: −1145.40 ± 0.08  mas / a
Physical Properties
Dimensions (0.609 ± 0.042)  M ☉
radius (0.592 ± 0.046)  R ☉
Effective temperature 3800  K
Rotation time 40 ± 12 d
Age 4.6 billion  a
Other names
and catalog entries
Cordoba Survey CD −39 ° 1419
Henry Draper Catalog HD 202560 [1]
Gliese catalog FY 825 [2]
Hipparcos catalog HIP 105090 [3]
SAO catalog SAO 212866 [4]
Tycho catalog TYC 7966-1201-1 [5]Template: Infobox star / maintenance / specification of the TYC catalog
2MASS catalog 2MASS J21171534-3852022 [6]
Other names AX Microscopii, Gliese 825, Gl 825, GC  29761, L PM  772, 1RXS  J211717.8-385150

Lacaille 8760 (also AX Microscopii ) is a red dwarf in the microscope constellation . Although it is too faint something without a telescope to be seen to, he heard at a distance of 12.9  light years to the neighboring stars of the sun . It was first included in his star catalog published posthumously in 1763 by the French astronomer Nicolas Louis de Lacaille . Lacaille observed the star in the southern sky from his observatory on the Cape of Good Hope .

In the past, the star was classified between the spectral classes K7 and M2. On the evening of September 12, 1979, the Irish astronomer Patrick B. Byrne discovered during observations at the SAAO that Lacaille 8760 is a flare star, whereupon the star was given the variable name AX Microscopii . For a flare star, however, it is relatively calm and breaks out less than once a day on average.

The orbit of Lacaille 8760 in the Milky Way is of relatively high eccentricity at 0.23 . Its closest approach to the sun happened around 20,000 years ago when it got closer than twelve light years. Because of its low mass (60% that of the sun), its estimated lifespan of 75 billion years is seven times that of the sun.

Despite various efforts by astronomers, no exoplanets have yet been discovered in an orbit around the star (as of 2018) .

Although Lacaille 8760 is the brightest red dwarf in the sky, it is still too faint for observation with the naked eye . It is also one of the largest and brightest known red dwarfs with 60% of the solar mass and 60% of the solar radius .

distance

Determining the distance for Lacaille 8760

source Parallax (mas) Distance (pc) Distance (Lj) Distance ( Pm )
Woolley et al. (1970) 260 ± 8 3.85 +0.12−0.11 12.5 ± 0.4 118.7 +3.8−3.5
Gliese & Jahreiß (1991) 258.6 ± 10.4 3.87 +0.16−0.15 12.6 ± 0.5 19.3 +5.0−4.6
van Altena et al. (1995) 258.8 ± 10.9 3.86 +0.17−0.16 12.6 +0.6−0.5 19.2 +5.2−4.8
Perryman et al. (1997) (Hipparcos) 253.37 ± 1.13 3.947 ± 0.018 12.87 ± 0.06 121.8 ± 0.5
Perryman et al. (1997) (Tycho)
van Leeuwen (2007) 253.41 ± 0.80 3.946 ± 0.012 12.87 ± 0.04 121.8 ± 0.4
RECONS TOP100 (2012) 253.44 ± 0.80 3.946 ± 0.012 12.87 ± 0.04 121.8 ± 0.4
Gaia DR2 (2018) 251.83 ± 0.06 3.971 ± 0.001 12.95 ± 0.01 122.46 ± 0.03

Non-trigonometric distance determinations are marked in italics . The most precise determination is marked in bold .

Web links

Individual evidence

  1. ↑ a b c d e AX Mic. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed on November 10, 2018 .
  2. ↑ a b c RECONS: THE ONE HUNDRED NEAREST STAR SYSTEMS. Retrieved April 1, 2015 .
  3. ↑ a b AX Mic. In: The International Variable Star Index (VSX). AAVSO , accessed November 10, 2018 .
  4. ↑ a b P. E. Kervella, F. Arenou, F. Mignard, F. Thévenin: Stellar and substellar companions of nearby stars from Gaia DR2. Binarity from proper motion anomaly . In: Astronomy & Astrophysics . 623, p. A72. arxiv : 1811.08902 . bibcode : 2019A & A ... 623A..72K . doi : 10.1051 / 0004-6361 / 201834371 .
  5. ^ Gautier, Thomas N., III et al .: Far Infrared Properties of M Dwarfs . arxiv : 0707.0464 .
  6. ^ Takeda, Genya et al .: Structure and Evolution of Nearby Stars with Planets II. Physical Properties of ~ 1000 Cool Stars from the SPOCS Catalog. Retrieved April 1, 2015 .
  7. ↑ Croswell, Ken: The Brightest Red Dwarf. Retrieved April 1, 2015 .
  8. ↑ Byrne, PB: Gliese 825 - A new flare star . bibcode : 1981MNRAS.195..143B .
  9. ↑ Allen, C .; Herrera, MA: The Galactic Orbits of Nearby UV Ceti Stars . bibcode : 1998RMxAA..34 ... 37A .
  10. ^ García-Sánchez, J. et al .: Stellar encounters with the solar system . bibcode : 2001A & A ... 379..634G .
  11. ↑ Despain, KH: Low-mass evolution - Zero-age main sequence to asymptotic giant branch . bibcode : 1981ApJ ... 251..639D .
  12. ^ Carson, JC et al .: A Spitzer IRAC Imaging Survey for T Dwarf Companions Around M, L, and T Dwarfs: Observations, Results, and Monte Carlo Population Analyzes . arxiv : 1110.2191 .
  13. ↑ Odert, P. et al .: Habitability of M-type Stars - a Catalog of Nearby M Dwarfs . bibcode : 2008CEAB ... 32..149O .
  14. ^ Woolley R .; Epps EA; Penston MJ; Pocock SB: Woolley 825. Retrieved April 1, 2015 .
  15. ↑ Gliese, W. and Jahreiß, H .: Gl 825. Accessed April 1, 2015 .
  16. ^ Van Altena WF, Lee JT, Hoffleit ED : GCTP 5117. Retrieved April 1, 2015 .
  17. ↑ Perryman et al .: HIP 105090. Retrieved April 1, 2015 .
  18. ↑ Perryman et al .: HIP 105090. Retrieved April 1, 2015 .
  19. ^ Van Leeuwen F .: HIP 105090. Accessed April 1, 2015 .