Mapping radio emitting-region on low-mass stars and brown dwarfs
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Yu, S. Doyle, J.G.; Hallinan, G.; MacKinnon, A.L. (2011). Mapping radio emitting-region on low-mass stars and brown dwarfs. EPJ Web of Conferences 16 ,
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.