WISE 0825+2805
Brown dwarf in the constellation Cancer
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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.[3] It is about 21.4 light-years away from Earth in the Cancer constellation.[6] 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.[4]
WISE 0825+2805 Credit: JWST/MIRI; Faherty et al. | |
| Observation data Epoch 2000 Equinox 2000 | |
|---|---|
| Constellation | Cancer[1] |
| Right ascension | 08h 25m 07.35720s[2] |
| Declination | +28° 05′ 48.5592″[2] |
| Characteristics | |
| Spectral type | Y0.5[3] |
| Apparent magnitude (J) | 22.53±0.10 |
| Apparent magnitude (H) | 23.09±0.18 |
| Astrometry | |
| Radial velocity (Rv) | −18.7±3.4[4] km/s |
| Proper motion (μ) | RA: −66.7±0.9 mas/yr[2] Dec.: −235.8±0.9 mas/yr[2] |
| Parallax (π) | 152.6±2.0 mas[2] |
| Distance | 21.4 ± 0.3 ly (6.55 ± 0.09 pc) |
| Details | |
| Mass | 3.7±0.2[4] or 11±2[5] MJup |
| Radius | 1.11±0.02[5] or 1.144±0.002[4] RJup |
| Surface gravity (log g) | 3.85±0.02[4] or 4.33+0.07 −0.09[5] cgs |
| Temperature | 359±3[4] K |
| Metallicity | = 0.64±0.05[5] |
| Age | 414±23[4] Myr or 2[5] Gyr |
| Other designations | |
| WISEA J082507.37+280548.2, WISE J082507.35+280548.5 | |
| Database references | |
| SIMBAD | data |
![{\displaystyle {\begin{smallmatrix}\left[{\mathrm {M} }/{\mathrm {H} }\right]\end{smallmatrix}}}](http://wikimedia.org/api/rest_v1/media/math/render/svg/d9a106d03666c72cc54c1dff07a5637d3adda9a1)
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.[3]
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.[7] 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).[4] However, a 2026 study found little evidence that WISE 0825+2805 is part of any moving group, and 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.[5]