Abstract We present the detection of 2MASS J22282889-4310262 (2M2228), a T6/T6. 5 brown dwarf, using the Karl G. Jansky Very Large Array (VLA) archival data observed at C band (4–8 GHz) over two observing epochs (2 × 96 minutes). 2M2228 is detected at time and frequency averaged Stokes I and V peak flux densities of 67. 3 4. 9\ \ {Jy beam^-1} and 14. 4 ± 3. 0 μJybeam−1 in the first epoch and 107. 2 5. 2\ {Jy\ beam^-1} and −20. 7 ± 1. 2 μJybeam−1 in the second epoch. This discovery constitutes the eighth and, notably, the most rapidly rotating T dwarf detected to date at radio wavelengths. Our observations reveal highly polarised bursts at fractional polarisation ratios fc 50%. Using Stokes I light curves, we measure occurrence intervals of ~47 and ~58 minutes in the two observing epochs respectively with the first burst aligning within a half period timescale of the the previously measured mid infrared photometric period of 85. 8 ± 0. 32 minutes. We attribute the emission to the electron cyclotron maser emission (ECME) and constrain the magnetic field strength to B ≳ 1. 4 kG. We emphasise that the periods inferred are provisional considering the short observing durations. The combination of previously demonstrated atmospheric stability and newly detected radio emission in 2M2228 makes it a promising laboratory for testing magnetospheric currents-driven auroral models. Future coordinated James Webb Space Telescope (JWST) and radio observations will further probe the link between auroral activity and atmospheric dynamics in this brown dwarf.
Wandia et al. (Sun,) studied this question.