| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 04h 15m 19.54s |
| Declination | −09° 35′ 06.6″ |
| Characteristics | |
| Spectral type | T8V |
| Apparent magnitude (Y) | 16.438 ± 0.009[1] |
| Apparent magnitude (J) | 15.343 ± 0.004[1] |
| Apparent magnitude (H) | 15.666 ± 0.012[1] |
| Apparent magnitude (Ks) | 15.658 ± 0.023[1] |
| Astrometry | |
| Proper motion (μ) | RA: 2214.3 ± 1.2[2]mas/yr Dec.: 535.9 ± 1.2[2]mas/yr |
| Parallax (π) | 175.2±1.7 mas[2] |
| Distance | 18.6 ± 0.2 ly (5.71 ± 0.06 pc) |
| Details[3] | |
| Mass | 36±3 MJup |
| Radius | 0.800±0.004 RJup |
| Luminosity (bolometric) | 10−5.70+0.04 −0.01 L☉ |
| Surface gravity (log g) | 5.14±0.03 cgs |
| Temperature | 758+18 −3 K |
| Metallicity | 0.28±0.02 dex |
| Age | 4-6 Gyr |
| Other designations | |
| 2MASS 0415-0935; 2MASSI J0415195−093506; 2MASSW J0415195−093506 | |
| Database references | |
| SIMBAD | data |
  2MASS 0415−0935 Location of 2MASS 0415−0935 in the constellationEridanus | |
2MASS J04151954−0935066 (also abbreviated to2MASS 0415−0935) is abrown dwarf ofspectral class T8,[2][4] in the constellationEridanus about 18.6light-years from Earth.[2] This is a reference (standard) object for the definition of the T8 spectral class.[5]
2MASS 0415−0935 was discovered in 2002 by Adam J. Burgasser et al. fromTwo Micron All-Sky Survey (2MASS), conducted from 1997 to 2001. Follow-up observations were made in 1998–2001 using the Near-Infrared Camera, mounted on thePalomar 60 inch (1.5 m) Telescope; CTIO Infrared Imager (CIRIM) and Ohio State Infrared Imager/Spectrometer (OSIRIS), mounted on theCerro Tololo Inter-American Observatory (CTIO) 1.5 m Telescope; and some additional observations were made using the Near Infrared Camera (NIRC), mounted on theKeck I 10 m telescope, and nearinfrared camera D78, mounted on thePalomar 5 mHale Telescope. In 2002 Burgasser et al. published a paper, where they defined new spectral subtypes T1—T8, and presented discovery of 11 new T-type brown dwarfs, among which also was 2MASS 0415−0935 — object of the latest known by the time spectral type T8. These 11 objects were among the earliest T-type brown dwarfs ever discovered: before this, the total number of known T-type objects was 13, and these discoveries increased it up to 24 (apart from additional T-type dwarfs, identified by Geballe et al. 2001 inSDSS data).[6]
Currently the most precise distance estimate of 2MASS 0415−0935 is published in 2012 by Dupuy & Liutrigonometric parallax, measured under The Hawaii Infrared Parallax Program: 175.2 ± 1.7milliseconds of arc, corresponding to a distance 5.71 ± 0.05pc, or 18.62 ± 0.18ly.[2] A less precise parallax of this object, measured underU.S. Naval Observatory Infrared Astrometry Program, was published in 2004 by Vrba et al.[7]
Position of 2MASS 0415−0935 shifts due to itsproper motion by 2.2553arcseconds per year (2.2782 ± 0.0012 arcsec, according to Dupuy & Liu (2012)[2]).
2MASS 0415-0935 belongs to thespectral classT8V; its surface temperature is about 750kelvins. As with other brown dwarfs of spectral type T, its spectrum was thought to be dominated bymethane, although by 2015 with the improved spectroscopic database many of the spectral lines were re-assigned to water.[5] TheResearch Consortium On Nearby Stars (RECONS) estimates the brown dwarf to be 0.03 solar masses.[8]
2MASS 0415-0935 was observed withNIRSpec on JWST. The observation constrained the abundances ofwater vapor (H2O), methane (CH4),carbon monoxide (CO),carbon dioxide (CO2) andammonia (NH4). The abundance ofhydrogen sulfide (H2S) was less well constrained andphosphine (PH3) was not detected, but an upper limit of its abundance was measured. The12CO/13CO ratio is97+9
−8, which is similar for2MASS J03552337+1133437 and similar to the ratio in the sun. It was shown that the current models of vertical mixing that predict the abundances of different molecules are inconsistent with measured abundances of carbon dioxide. 2MASS 0415-0935 joins a number of T and Y-dwarfs with missing phosphine, such asWISE 0359−5401, requiring a major revision ofphosphorus chemistry in brown dwarfs and possiblygiant planets.[3]
The other 10 brown dwarfs, presented inBurgasser et al. (2002):[6]
