Relationship between Envelope Structure and Energy Source of Non-Thermal Motions

Abstract

The ionization zone in the envelope of the late type stars is reasonably considered as a heat engine to transform some of the radiative energy into mechanical energy. This idea is suggestive for explaining Linsky and Haisch’s (1979) observation, which shows the sharp division into solar-type and non-solar type stars in the outer atmosphere. Also non-thermal velocity fields in “microturbulence” and in Wilson-Bappu effect are proposed to be formed essentially from this engine. Therefore, their envelope structure dependence observationally obtained is possibly explained by the envelope parameters (g, T_e) dependence of the generated mechanical energy flux in this layer. If “microturbulence” is not contaminated by the other surface activities, it is expected to show a clear relation with envelope parameters (g, T_e) similar to Wilson-Bappu effect.