Mapping radio emitting-region on low-mass stars and brown dwarfs
1 Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland
2 Centre for Astronomy, National University of Ireland, Galway, Ireland
3 The Department of Adult and Continuing Education, University of Glasgow, Scotland
a e-mail: firstname.lastname@example.org
Strong magnetic activity in ultracool dwarfs (UCDs, spectral classes later than M7) have emerged from a number of radio observations, including the periodic beams. The highly (up to 100%) circularly polarized nature of the emission point to an effective amplification mechanism of the high-frequency electromagnetic waves – the electron cyclotron maser (ECM) instability. Several anisotropic velocity distibution models of electrons, including the horseshoe distribution, ring shell distribution and the loss-cone distribution, are able to generate the ECM instability. A magnetic-field-aligned electric potential would play an significant role in the ECM process. We are developing a theoretical model in order to simulate ECM and apply this model to map the radio-emitting region on low-mass stars and brown dwarfs.
© Owned by the authors, published by EDP Sciences, 2011