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Cold brown dwarf in the constellation Sagittarius From Wikipedia, the free encyclopedia
CWISEP J1935-1546 (CWISEP J193518.59-154620.3 or Brown Dwarf W1935 or W1935) is a cold brown dwarf or planetary-mass object with a mass of 2-20 MJ[6] or 6-35 MJ[4] and a distance of 14.4 parsec (47 light-years).[3]
_(2024-103).png) Artist concept of the aurora in W1935 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Sagittarius[1] |
| Right ascension | 19h 35m 18.60792s[2] |
| Declination | −15° 46′ 20.8074″[2] |
| Characteristics | |
| Evolutionary stage | brown dwarf |
| Spectral type | ≥Y1[3] |
| Astrometry | |
| Radial velocity (Rv) | −36.9±5.1[4] km/s |
| Total velocity | 42.02±5.33[4] km/s |
| Proper motion (μ) | RA: 290.2±11.6 mas/yr[3] Dec.: 43.1±11.5 mas/yr[3] |
| Parallax (π) | 69.3 ± 3.8 mas[3] |
| Distance | 47 ± 3 ly (14.4 ± 0.8 pc) |
| Details | |
| Mass | 6-35[4] MJup |
| Radius | 0.95±0.14[4] RJup |
| Surface gravity (log g) | 4.7±0.5[4] cgs |
| Temperature | 482±38[4] K |
| Age | 4.5±4.0[4] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
CWISEP J1935-1546 was discovered in 2019 by Marocco et al. as an extremely cold brown dwarf with a temperature range of 270-360 K and a distance of 5.6-10.9 parsec. It was discovered with the help of the python package XGBoost, using machine-learning algorithms and the CatWISE catalog, as well as the WiseView tool.[6] According to a NASA press release CWISEP J1935-1546 was discovered by the security engineer[7] and citizen scientist Dan Caselden.[5] Follow-up observations with Spitzer revealed a very red object with ch1-ch2 of 3.24±0.31 mag.[6] Later Kirkpatrick et al. 2021 showed a temperature of 367±79 K (15-173 °C; 59-343 °F) and a parallax of 69.3±3.8 mas (14.43+0.84
−0.75 parsec) for this object. The spectral type was estimated to be later than Y1.[3] Observations with JWST found strong signatures of methane, carbon monoxide, carbon dioxide, water vapor and ammonia in the atmosphere of this brown dwarf. The abundance of hydrogen sulfide was measured, but the researchers don't mention its detection. Phosphine is undetected and the researchers only provide upper limits.[4]
At the 243rd meeting of the AAS it was announced that W1935, shows emission of methane. This is attributed to heating of the upper atmosphere by an aurora around W1935. Impacts of electrons with molecular hydrogen creates trihydrogen cation (H+
3) in gas giants with an aurora. Emission from H+
3 was not detected in W1935, likely due the higher density of the brown dwarf, which leads to a shorter lifetime of H+
3. Aurorae were discovered in the past around hotter brown dwarfs with radio telescopes. The solar system planets Jupiter and Saturn have an aurora because of interactions with the stellar wind and with particles from active moons, such as Enceladus and Io. The researchers propose that the aurora around W1935 is caused by either unaccounted internal processes or by external interactions with interstellar plasma or a nearby active moon. The researchers also announced that W1935 has a temperature inversion that is either caused by the aurora or has to do with internal energy transport. These results were later published in April 2024.[5][4]
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