Gliese 229

Gliese 229 (also designated as Gl 229 or GJ 229) is a binary system that has a red dwarf and the first brown dwarf discovered by astronomers. It is located 18.8 light years away in the constellation Lepus. The main star of the binary system has 58% of the mass of the Sun,^[1] 69% of the Sun's radius, and a very low projected rotation velocity of 1 km/s at the stellar equator.

The larger object in the picture is Gliese 229, the red dwarf, and the smaller and fainter object in the picture is the brown dwarf Gliese 229b.

The star sometimes randomly gets brighter in luminosity because it is a low activity flare star, which means there is magnetic activity on its surface that causes it to get randomly brighter. It gives off light in the H and K bands due to calcium. It also gives off X-rays from its corona, caused by the interaction between magnetic loops and the gas in its outer atmosphere.^[2] There are no large spots on the star that have been detected.^[3]

The star is moving through space with a velocity of +12 km/s in the U direction, –11 km/s in the V direction, and –12 km/s in the W direction.^[4] Its path around the Milky Way is a little bit squashed, with an eccentricity of 0.07. Its orbit is also tilted just a little bit, with an inclination of 0.005.^[3]

References

↑ Brandt, Timothy D.; Dupuy, Trent J.; Bowler, Brendan P.; Gagliuffi, Daniella C. Bardalez; Faherty, Jacqueline; Brandt, G. Mirek; Michalik, Daniel (2020). "A Dynamical Mass of 70±5 Jupiter Masses for Gliese 229B, the First Imaged T Dwarf". Astronomical Journal. 160: 4. arXiv:1910.01652. doi:10.3847/1538-3881/abb45e. S2CID 222277091.
↑ Schmitt JHMM; Fleming TA; Giampapa MS (September 1995). "The X-Ray View of the Low-Mass Stars in the Solar Neighborhood". Astrophys. J. 450 (9): 392–400. Bibcode:1995ApJ...450..392S. doi:10.1086/176149.
↑ ^3.0 ^3.1 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 (2): 119–130. Bibcode:1985MNRAS.214..119B. doi:10.1093/mnras/214.2.119.
↑ Gliese, W. (1969). "Catalogue of Nearby Stars". Veröffentlichungen des Astronomischen Rechen-Instituts Heidelberg. 22: 1. Bibcode:1969VeARI..22....1G.

[Brandt2019-1] Brandt, Timothy D.; Dupuy, Trent J.; Bowler, Brendan P.; Gagliuffi, Daniella C. Bardalez; Faherty, Jacqueline; Brandt, G. Mirek; Michalik, Daniel (2020). "A Dynamical Mass of 70±5 Jupiter Masses for Gliese 229B, the First Imaged T Dwarf". Astronomical Journal. 160: 4. arXiv:1910.01652. doi:10.3847/1538-3881/abb45e. S2CID 222277091.

[Schmitt-2] Schmitt JHMM; Fleming TA; Giampapa MS (September 1995). "The X-Ray View of the Low-Mass Stars in the Solar Neighborhood". Astrophys. J. 450 (9): 392–400. Bibcode:1995ApJ...450..392S. doi:10.1086/176149.

[mnras214-3] 3.0 ^3.1 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 (2): 119–130. Bibcode:1985MNRAS.214..119B. doi:10.1093/mnras/214.2.119.

[4] Gliese, W. (1969). "Catalogue of Nearby Stars". Veröffentlichungen des Astronomischen Rechen-Instituts Heidelberg. 22: 1. Bibcode:1969VeARI..22....1G.

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