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Origin of Electron Cyclotron Maser Induced Radio Emissions at Ultracool Dwarfs: Magnetosphere-Ionosphere Coupling Currents

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posted on 03.07.2013, 12:36 by J. D. Nichols, Matthew R. Burleigh, Sarah L. Casewell, Stanley W. H. Cowley, Graham Anthony Wynn, J.T. Clarke, A.A. West
A number of ultracool dwarfs emit circularly polarized radio waves generated by the electron cyclotron maser instability. In the solar system such radio is emitted from regions of strong auroral magnetic-field-aligned currents. We thus apply ideas developed for Jupiter’s magnetosphere, being a well-studied rotationally dominated analog in our solar system, to the case of fast-rotating UCDs. We explain the properties of the radio emission from UCDs by showing that it would arise from the electric currents resulting from an angular velocity shear in the fast-rotating magnetic field and plasma, i.e., by an extremely powerful analog of the process that causes Jupiter’s auroras. Such a velocity gradient indicates that these bodies interact significantly with their space environment, resulting in intense auroral emissions. These results strongly suggest that auroras occur on bodies outside our solar system.

History

Citation

The Astrophysical Journal, 2012, 760 (1)

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

The Astrophysical Journal

Publisher

IOP Publishing (Institute of Physics)

issn

0004-637X

eissn

1538-4357

Copyright date

2012

Available date

03/07/2013

Publisher version

http://iopscience.iop.org/0004-637X/760/1/59/

Language

en