CWISEP J1935-1546

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 or 6-35  and a distance of 14.4 parsec (47 light-years).

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. According to a NASA press release CWISEP J1935-1546 was discovered by the security engineer and citizen scientist Dan Caselden. Follow-up observations with Spitzer revealed a very red object with ch1-ch2 of 3.24±0.31 mag. 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 ($-36.9$ parsec) for this object. The spectral type was estimated to be later than Y1.

At the 243rd meeting of the AAS it was announced that W1935, shows emission of methane. This is attributed to an aurora around W1935. 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.