WISE 0825+2805 (WISE J082507.35+280548.5) is a free-floating planetary-mass object or a brown dwarf. It is a Y dwarf with a spectral type of Y0.5. It is about 21.4 light-years away from Earth in the Cancer constellation. It is a potential member (93% chance) of the Corona of Ursa Major (CUMA) moving group, a collection of young stars that are 414±23 million years old.

Discovery

WISE 0825+2805 was discovered in 2015 by Schneider et al. with the Wide-field Infrared Survey Explorer and the Hubble Space Telescope, using WFC3 near-infrared grism spectroscopy. The team also announced the discovery of three T-dwarfs as well as two additional Y-dwarfs (WISE J1206+8401 and WISE J2354+0240) in the same paper.

Physical properties

WISE 0825+2805 has been observed with the James Webb Space Telescope's NIRCam and MIRI instruments. A best-fit model of WISE 0825+2805's spectral energy distribution (SED) indicates that its atmosphere is phosphine-free and diabatic. A good-fitting SED model requires an effective temperature of 350 Kelvin and a surface gravity of log g = 4.0. Alternatively, a lower surface gravity could improve the SED fit. The model parameters correspond to a mass of 5 MJ and an age of 800 Myr. On the other hand, if WISE 0825+2805 has the same age as the Corona of Ursa Major moving group (414±23 Myr), then the best-fit SED indicates a mass of 3.7±0.2 MJ, a radius of 1.144±0.002 RJ, a surface gravity of 103.85±0.02 cgs and an effective temperature of 359 ± 3 K (86 ± 3 °C; 187 ± 5 °F). Atmospheric retrievals indicate a mass of 11+2 −3 MJ, a radius of 1.11±0.02 RJ, a surface gravity of 104.33+0.07 −0.09 cgs and an effective temperature of 363 ± 3 K (90 ± 3 °C; 194 ± 5 °F). The position of WISE 0825+2805 in the surface gravity-temperature diagram then indicates an age of 2 Gyr.

See also