WISEPA J062309.94-045624.6

12.28 ±13.06 1.11 ±0.14 624 ±40 63 WISEPA J062309.94−045624.6 (also called WISE J0623−0456) is a brown dwarf of spectral type T8. It is the coldest brown dwarf with a radio emission (as of October 2024).

WISE J0623−0456 was discovered in 2011 with the Wide-field Infrared Survey Explorer and a spectrum with the NASA Infrared Telescope Facility confirmed it as a T8-dwarf. WISE J0623−0456 was identified as a radio source with the Australian SKA Pathfinder. Follow-up observations were carried out with the Australia Telescope Compact Array (ATCA) and MeerKAT. The source showed a double-peaked pulsed emission, with a period of 1.889 ± 0.018 hours in ATCA and 1.912 ± 0.005 hours in MeerKAT. The source has a radio luminousity of 1014.8 erg s−1 Hz−1 and is comparable to other radio bright ultracool dwarfs with a similar spectral type. The radio emission of WISE J0623−0456 is strongly circularly polarized and periodic. The researchers therefore think that the radio emission comes from electron cyclotron maser instability (ECMI), which is connected to aurora in ultracool dwarfs. The researchers find that the magnetic field has a strength of at least B 0.71 kG. Another work finds that the shape of the lightcurve can be reproduced by active field lines (AFLs). This work also found that the brown dwarf is likely seen pole-on. The rotation and magnetic axes are misaligned significantly (similar to Uranus and Neptune) and the magnetic cycle is likely longer than 6 months. M- and L-dwarfs can produce the observed radio luminosities on their own, but cooler T- and Y-dwarfs don't have the necessary corona to produce the radio emission. The alternative is that the plasma is fed to the magnetosphere from a companion, similar to the role of Io for the aurora on Jupiter.