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Session 119 - Active Stars.
Oral session, Thursday, January 16
Harbour C,

[119.01] Atmospheric Heating and Quiescent Radio Emission in Active Stars

V. Airapetian (CSC/NASA/GSFC), G. Holman (NASA/GSFC)

Observational surveys of magnetically active stars of K to M spectral classes have revealed an interrelationship between their "quiescent" soft X-ray and microwave luminosities. While the quiescent soft X-ray emission has a thermal coronal-like nature, the quiescent microwave emission is usually nonthermal gyrosynchrotron radiation. This correlation is discussed in terms of the ability of heating mechanisms to explain the required number of mildly relativistic electrons and their flat energy spectra. We analyze the observational radio signatures of two heating/acceleration mechanisms. One mechanism proposes that electrons are accelerated in current sheets in the stellar coronae, while the other considers MHD turbulence cascading down to smaller scales and accelerating particles by fast Alfven waves or current instability. The universality of the soft X-ray-microwave luminosity correlation in a wide range of active stars can be understood in terms of the ability of both mechanisms to explain such a correlation.

Program listing for Thursday