DENIS 0255−4700
Star in the constellation Eridanus
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DENIS 0255−4700 is an extremely faint brown dwarf 15.9 light-years (4.9 parsecs) from the Solar System in the southern constellation of Eridanus. It is the closest isolated L-type brown dwarf (no undiscovered L-dwarfs are expected to be closer), and only after the binary Luhman 16. It is also the faintest brown dwarf (with the absolute magnitude of MV = 24.44) having measured visible magnitude.[3] A number of nearer T and Y-type dwarfs are known, specifically WISE 0855−0714, Epsilon Indi B and C, SCR 1845-6357 B, and UGPS 0722−05.
  DENIS 0255−4700 Location of DENIS 0255−4700 in the constellation Eridanus | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Eridanus[1] |
| Right ascension | 02h 55m 03.693s[2] |
| Declination | −47° 00′ 51.36″[2] |
| Apparent magnitude (V) | 22.9[3] |
| Characteristics | |
| Evolutionary stage | brown dwarf[4] |
| Spectral type | L8/L9[5] |
| Apparent magnitude (R) | ~20.1[6] |
| Apparent magnitude (I) | ~17.2[6] |
| Apparent magnitude (J) | ~13.2[6] |
| Astrometry | |
| Proper motion (μ) | RA: 1,012.445 mas/yr[2] Dec.: −554.031 mas/yr[2] |
| Parallax (π) | 205.4251±0.1857 mas[2] |
| Distance | 15.88 ± 0.01 ly (4.868 ± 0.004 pc) |
| Absolute magnitude (MV) | 24.44[3] |
| Details | |
| Mass | 0.0578[7] M☉ |
| Radius | 0.0776[7] R☉ |
| Luminosity | 0.0000154[7] L☉ |
| Temperature | ~1300[5][7] K |
| Rotation | 1.7 hours[4] |
| Rotational velocity (v sin i) | 40.8±8.0[4] km/s |
| Age | 0.3–10[5] Gyr |
| Other designations | |
| GJ 10402,[8] 2MUCD 10158, DENIS-P J025503.3−470049, 2MASS J02550357−4700509, DENIS-P J025503.5−470050, DENIS-P J0255.0−4700, 2MASSI 0255035−470050 | |
| Database references | |
| SIMBAD | data |
History of observations
DENIS 0255−4700 was identified for the first time as a probable nearby object in 1999.[9] Its proximity to the Solar System was established by the RECONS group in 2006 when its trigonometric parallax was measured.[3] DENIS 0255-4700 has a relatively small tangential velocity of 27.0 ± 0.5 km/s.[5] The discovery of DENIS 0255-4700 was made by a photometric selection (very red I-J color) performed by Xavier Delfosse using the DENIS survey and optical spectroscopic reconnaissance observations obtained with Low-Resolution Imaging Spectrograph at the Keck II telescope in Mauna Kea observatory (Big island of Hawaii) on December 23, 1998, by Eduardo L Martín and colleagues.[10]
Properties
The photospheric temperature of DENIS 0255−4700 is estimated at 1300 K.[5] Its atmosphere in addition to hydrogen and helium contains water vapor, methane and possibly ammonia.[11] The mass of DENIS 0255−4700 lies in the range from 25 to 65 Jupiter masses corresponding to the age range from 0.3 to 10 billion years.[5] The brown dwarf is rotating rapidly with the period of 1.7 hours, and its rotational axis is inclined 40 degrees from the line-of-sight.[4]