KPNO-Tau 12
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| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Taurus[1] |
| Right ascension | 04h 19m 01.28s[2] |
| Declination | +28° 02′ 48.1″[2] |
| Apparent magnitude (V) | 23.228±0.023[3] |
| Characteristics | |
| Evolutionary stage | low-mass brown dwarf or planetary-mass object |
| Spectral type | M9.25±0.5[4] |
| Astrometry | |
| Proper motion (μ) | RA: 7.09±5.60 mas/yr[5] Dec.: −28.41±5.27 mas/yr[5] |
| Distance | 473 ± 49 ly (145±15 pc)[5] |
| Details | |
| Mass | 12.7+1.6 −1.8[6] MJup |
| Radius | 2.22+0.11 −0.17[6] RJup |
| Luminosity (bolometric) | 10−2.99±0.16[5] L☉ |
| Temperature | 2170±200[5] K |
| Rotational velocity (v sin i) | 5.0[7] km/s |
| Age | 1-10[5] Myr |
| Other designations | |
| KPNO-Tau 12, 2MASS J04190126+2802487, SSTtau 041901.2+280248, TIC 58285609, UGCS J041901.27+280248.3, WISE J041901.26+280248.2, Gaia DR2 164487734085116800 | |
| Database references | |
| SIMBAD | data |
KPNO-Tau 12 (also called 2MASS J0419012+280248) is a low-mass brown dwarf or free-floating planetary-mass object that is surrounded by a protoplanetary disk, actively accreting material from it.[8]
KPNO-Tau 12 was identified in 2003 in data from a survey of the Taurus Molecular Clouds taken with a telescope at the Kitt Peak National Observatory (KPNO) and 2MASS. The object was observed with the MMT Observatory/Blue Channel spectrometer and with Keck/LRIS. KPNO-Tau 12 showed a spectral type of M9 and also showed strong Hydrogen-alpha emission. At the time its mass was estimated to be around 0.02 M☉ (or 21 MJ), which would make it a brown dwarf.[8] Since then several works found that it likely has a mass near or below the deuterium-burning limit, which makes this object a low-mass brown dwarf or planetary-mass object (e.g. 14.6 MJ,[3] 13.6 MJ,[9] 6-7 MJ,[4] 16.5 MJ,[10] 17.8+6.7
−4.6 MJ,[11] 12.7+1.6
−1.8 MJ[6]).
A few other free-floating planetary-mass objects are known in the Taurus Clouds.[12][13] These include three other objects with possible disks around them.[13]
Atmosphere
Observations with Keck/LRIS showed several absorption features. These are titanium oxide, calcium hydride, vanadium oxide, sodium and potassium.[8] A spectrum with Keck/NIRSPEC was interpreted to be consistent with very low gravity. This is typical for young sources.[14] Several re-classifications of the spectral type were made over the years. In 2013 it was re-classified as a M9.25±0.5.[4] In 2018 it was re-classified as a L0.7±1.1, which could make this object an early L-dwarf.[5] A spectrum observed with VLT/SINFONI was published in 2022, estimating a spectral type of M9.8.[15]
