2MASS 0532+8246

2MASS 0532+8246 (full designation 2MASS J05325346+8246465) is possibly the first brown dwarf observed in the galactic halo of the Milky Way, and the first known substellar subdwarf star.[3][2] It was discovered from Two Micron All-Sky Survey data, and verified by observations at Palomar Observatory and W. M. Keck Observatory.[2] It has a low metallicity, which indicates it is an old star.[2] With an age of 12.5 billion years, it is the oldest known brown dwarf star.

2MASS J05325346+8246465
Observation data
Epoch J2000[1]      Equinox J2000[1]
Constellation Camelopardalis
Right ascension 05h 32m 53.46s[1]
Declination +82° 46′ 46.5″[1]
Characteristics
Spectral type L7[1]
Astrometry
Parallax (π)40.2369 ± 0.6389[1] mas
Distance81 ± 1 ly
(24.9 ± 0.4 pc)
Details
Mass0.077–0.085 M☉
Metallicity0.1–0.01[2]
Age10–15 Gyr
Other designations
2MASS J05325346+8246465,[1]
2MASS 0532+8246
Database references
SIMBADdata

The mass and temperature of 2MASS 0532+8246 makes it a rare object in stellar-substellar gap between conventional stars and brown dwarfs.[4]

References
  1. "2MASS J05325346+8246465 -- Brown Dwarf (M<0.08solMass)". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2018-12-04.
  2. Burgasser, Adam J. et al. (2003) The First Substellar Subdwarf? Discovery of a Metal-Poor L Dwarf with Halo Kinematics. The Astrophysical Journal, 592(2) 1186.
  3. Faherty, Jacqueline K.; Burgasser, Adam J.; Walter, Frederick M.; Van der Bliek, Nicole; Shara, Michael M.; Cruz, Kelle L.; West, Andrew A.; Vrba, Frederick J.; Anglada-Escud, Guillem (2012). "The Brown Dwarf Kinematics Project (BDKP). III. Parallaxes for 70 Ultracool Dwarfs". The Astrophysical Journal. 752 (1): 56. arXiv:1203.5543. Bibcode:2012ApJ...752...56F. doi:10.1088/0004-637X/752/1/56. S2CID 18160586.
  4. Zhang 张曾华, Z. H.; Homeier, D.; Pinfield, D. J.; Lodieu, N.; Jones, H. R. A.; Allard, F.; Pavlenko, Ya. V. (2017), "Primeval very low-mass stars and brown dwarfs – II. The most metal-poor substellar object", Monthly Notices of the Royal Astronomical Society, 468: 261–271, arXiv:1702.02001, doi:10.1093/mnras/stx350, S2CID 54847595


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