Gliese 229

Gliese 229

Gliese 229 A and B.
Observation data
Epoch J2000      Equinox J2000
Constellation Lepus
Right ascension 06h 10m 34.6154s[1]
Declination −21° 51′ 52.715″[1]
Apparent magnitude (V) 8.14
Characteristics
Spectral type M1Ve[2]
U−B color index +1.222[2]
B−V color index +1.478[2]
Variable type Flare star
Astrometry
Radial velocity (Rv) +3.9[3] km/s
Proper motion (μ) RA: –137.01[1] mas/yr
Dec.: –714.05[1] mas/yr
Parallax (π) 173.19 ± 1.12[1] mas
Distance 18.8 ± 0.1 ly
(5.77 ± 0.04 pc)
Absolute magnitude (MV) 9.33
Details
Mass 0.58[4] M☉
Radius 0.69[5] R☉
Temperature 3,700[6] K
Rotational velocity (v sin i) 1[7] km/s
Other designations
BD-21°1377, HD 42581, HIP 29295, LHS 1827, NSV 2863, SAO 171334, TYC 5945- 765-1

Gliese 229 (also written as Gl 229 or GJ 229) is a red dwarf star about 19 light years away in the constellation Lepus. It has 58% of the mass of the Sun,[4] 69% of the Sun's radius,[5] and a very low projected rotation velocity of 1 km/s at the stellar equator.[7]

The star is known to be a low activity flare star, which means it undergoes random increases in luminosity because of magnetic activity at the surface. The spectrum shows emission lines of calcium in the H and K bands. The emission of X-rays has been detected from the corona of this star.[8] These may be caused by magnetic loops interacting with the gas of the star's outer atmosphere. No large-scale star spot activity has been detected.[2]

In 1994 a substellar companion was imaged and it was confirmed in 1995. Gliese 229B is a brown dwarf orbiting the star; although it is too small to sustain hydrogen-burning nuclear fusion, with a mass of 20 to 50 times that of Jupiter (0.02 to 0.05 solar masses) it is still too massive to be a planet. Gliese 229B was the first confirmed substellar-mass object. This object has a surface temperature of 950 K.[9]

The space velocity components of this star are U = +12, V = –11 and W = –12 km/s.[10] The orbit of this star through the Milky Way galaxy has an eccentricity of 0.07 and an orbital inclination of 0.005.[2]

References

  1. ^ 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. 
  2. ^ a b c d e Byrne, P. B.; Doyle, J. G.; Menzies, J. W. (May 1, 1985). "Optical photometry and spectroscopy of the flare star Gliese 229 (=HD42581)". Monthly Notices of the Royal Astronomical Society 214: 119–130. Bibcode 1985MNRAS.214..119B. 
  3. ^ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick. Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. http://adsabs.harvard.edu/abs/1967IAUS...30...57E. Retrieved 2009-10-19. 
  4. ^ a b Zechmeister, M.; Kürster, M.; Endl, M. (October 2009). "The M dwarf planet search programme at the ESO VLT + UVES. A search for terrestrial planets in the habitable zone of M dwarfs". Astronomy and Astrophysics 505 (2): 859–871. Bibcode 2009A&A...505..859Z. doi:10.1051/0004-6361/200912479. 
  5. ^ a b White, Stephen M.; Jackson, Peter D.; Kundu, Mukul R. (December 1989). "A VLA survey of nearby flare stars". Astrophysical Journal Supplement Series 71: 895–904. Bibcode 1989ApJS...71..895W. doi:10.1086/191401. 
  6. ^ Morales, J. C.; Ribas, I.; Jordi, C. (February 2008). "The effect of activity on stellar temperatures and radii". Astronomy and Astrophysics 478 (2): 507–512. Bibcode 2008A&A...478..507M. doi:10.1051/0004-6361:20078324.  Data from CDS table J/A+A/478/507.
  7. ^ a b Reiners, A. (May 2007). "The narrowest M-dwarf line profiles and the rotation-activity connection at very slow rotation". Astronomy and Astrophysics 467 (1): 259–268. arXiv:astro-ph/0702634. Bibcode 2007A&A...467..259R. doi:10.1051/0004-6361:20066991. 
  8. ^ Schmitt JHMM, Fleming TA, Giampapa MS (September 1995). "The X-Ray View of the Low-Mass Stars in the Solar Neighborhood". Ap J. 450 (9): 392–400. Bibcode 1995ApJ...450..392S. doi:10.1086/176149. 
  9. ^ Geißler, K.; Chauvin, G.; Sterzik, M. F. (March 2008). "Mid-infrared imaging of brown dwarfs in binary systems". Astronomy and Astrophysics 480 (1): 193–198. Bibcode 2008A&A...480..193G. doi:10.1051/0004-6361:20078229. 
  10. ^ Gliese, W. (1969). "Catalogue of Nearby Stars". Veröffentlichungen des Astronomischen Rechen-Instituts Heidelberg. Bibcode 1969VeARI..22....1G. 

External links

Stars of Lepus
Bayer
Flamsteed
Nearby