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Star in the constellation Libra From Wikipedia, the free encyclopedia
WISE 1541−2250 (full designation WISEPA J154151.66−225025.2) is a sub-brown or brown dwarf of spectral class Y0.5,[2] located in the constellation Libra at approximately 18.6 light-years from Earth.[3] This object received popular attention when its discovery was announced in 2011 at a distance estimated to be only about 9 light-years, which would have made it the closest brown dwarf known.[6] (For really close brown dwarfs see, for example, Luhman 16, WISE 1506+7027, Epsilon Indi Ba, Bb, or UGPS 0722-05). It is not the farthest known Y-type brown dwarf to Earth.
Observation data Epoch MJD 55424.68[1] Equinox J2000[1] | |
---|---|
Constellation | Libra |
Right ascension | 15h 41m 51.57s[1] |
Declination | −22° 50′ 25.03″[1] |
Characteristics | |
Spectral type | Y0.5[2] |
Apparent magnitude (J (MKO filter system)) | 21.16 ± 0.36[1] |
Apparent magnitude (H (MKO filter system)) | 20.99 ± 0.52[1] |
Astrometry | |
Proper motion (μ) | RA: −895±5 mas/yr[3] Dec.: −88±5 mas/yr[3] |
Parallax (π) | 166.9 ± 2.0 mas[4] |
Distance | 19.5 ± 0.2 ly (5.99 ± 0.07 pc) |
Details | |
Mass | 12 (8–12)[5] MJup |
Radius | 1.01 (1.01–1.07)[5] RJup |
Surface gravity (log g) | 4.50 (4.25–4.5)[5] cgs |
Temperature | 350[5] K |
Other designations | |
Database references | |
SIMBAD | data |
Location of WISE 1541−2250 in the constellation Libra |
WISE 1541−2250 was discovered in 2011 from data collected by the Wide-field Infrared Survey Explorer (WISE) in the infrared at a wavelength of 40 cm (16 in), whose mission lasted from December 2009 to February 2011. WISE 1541−2250 has two discovery papers: Kirkpatrick et al. (2011) and Cushing et al. (2011) with mostly the same authors and published nearly simultaneously.[1][5]
Currently the most accurate distance estimate of WISE 1541−2250 is a trigonometric parallax, published in 2014 by Tinney et al.: 0.1751 ± 0.0044 arcsec, corresponding to a distance 5.71+0.15
−0.14 pc, or 18.6 ± 0.5 ly.[3]
For several months after its discovery, before the publication of its parallax by Kirkpatrick et al. in 2012,[2] WISE 1541−2250 was considered to be the nearest known brown dwarf at approximately 9 light-years from the Sun, and the seventh-nearest of all star systems, at slightly more than twice the distance of the nearest known star system Alpha Centauri. This view existed because of a very rough preliminary parallax with a baseline of 1.2 years, published in the discovery paper: 0.351 ± 0.108 arcsec, corresponding to a distance 2.8+1.3
−0.6 pc, or 9.3+4.1
−2.2 ly.[1] Also, there were other estimates: spectrophotometric distance estimate 8.2 pc (26.7 ly),[1] and photometric distance estimate 1.8+0.2
−0 pc (5.9+0.6
−0 ly).[5]
WISE 1541−2250 has proper motion of about 899 milliarcseconds per year.[3]
WISE 1541−2250 is among the first known examples of a Y-class brown dwarf, the coldest spectral class of stars, and has temperature about 350 K[5] (about 77 °C / 170 °F). Its spectral class is Y0.5[2] (initially was estimated as Y0).[1][5] Modelling of WISE 1541−2250 has shown that there could be water clouds in the atmosphere of this brown dwarf. Models however struggle to reproduce the spectrum even with water clouds.[7]
The other six discoveries of brown dwarfs, published in Cushing et al. (2011):[5]
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