Main-oval auroral emission from a T6 brown dwarf: observations, modeling, and astrometry
Fuente:
arXiv
Gespeichert in:
| Hauptverfasser: | , , , , , |
|---|---|
| Format: | Preprint |
| Veröffentlicht: |
2025
|
| Schlagworte: | |
| Online-Zugang: | |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| _version_ | 1866908353045725184 |
|---|---|
| author | Guirado, J. C. Climent, J. B. Bergasa, J. D. Pérez-Torres, M. A. Marcaide, J. M. Peña-Moñino, L. |
| author_facet | Guirado, J. C. Climent, J. B. Bergasa, J. D. Pérez-Torres, M. A. Marcaide, J. M. Peña-Moñino, L. |
| contents | 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_04506 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Main-oval auroral emission from a T6 brown dwarf: observations, modeling, and astrometry Guirado, J. C. Climent, J. B. Bergasa, J. D. Pérez-Torres, M. A. Marcaide, J. M. Peña-Moñino, L. Solar and Stellar Astrophysics Earth and Planetary Astrophysics 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. |
| title | Main-oval auroral emission from a T6 brown dwarf: observations, modeling, and astrometry |
| topic | Solar and Stellar Astrophysics Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2505.04506 |