TY - JOUR
AU1 - Guirado, J. C.
AU2 - Climent, J. B.
AU3 - Bergasa, J. D.
AU4 - Pérez-Torres, M. A.
AU5 - Marcaide, J. M.
AU6 - Peña-Moñino, L.
AB - Abstract:From a series of 5 GHz VLBA radio observations taken over 1-yr span, we present the detection of compact highly-polarized radio emission from the T6 brown dwarf WISE J112254.72+255022.2 compatible with electron cyclotron maser emission. Both the total and polarized lightcurves show variability in correspondence with a rotation period of 1.95+/-0.03 hr. Comparison with models indicates that the quasi-steady radio emission of this brown dwarf is produced in circumpolar auroral rings, with remarkable similarity to the main-oval auroras in Jupiter. We have detected a large 100% polarized flare in one of the VLBA epochs (2022.82) which may imply the existence of active longitudes in the auroral rings with a non-axisymmetric beaming cone radiation pattern, similar to the dusk/dawn asymmetries seen in the Jovian radio emissions. We also present a high-precision astrometric analysis of the sky motion of WISE J112254.72+255022.2, resulting in revised values of proper motion and parallax with an improvement in precision of one order of magnitude. The common kinematics of WISE J112254.72+255022.2 with its wide companion, the M-dwarf LHS 302, is confirmed with submilliarcsecond precision, suggesting that this brown dwarf may have formed by gravitational fragmentation of the outer part of a protostellar disc around LHS 302. The astrometric analysis imposes very tight bounds to the presence of low-mass companions around WISE J112254.72+255022.2, ruling out objects more massive than Saturn. Our results strengthen the analogy between radio emitting brown dwarfs and the magnetized planets of our solar system.
TI - Main-oval auroral emission from a T6 brown dwarf: observations, modeling, and astrometry
JF - Astrophysics
DO - 10.48550/arxiv.2505.04506
DA - 2025-05-07
UR - https://www.deepdyve.com/lp/arxiv-cornell-university/main-oval-auroral-emission-from-a-t6-brown-dwarf-observations-modeling-3dg6tRAX0l
VL - 2025
IS - 2505
DP - DeepDyve
ER -