High Resolution Studies of F and G Star Transition Layer Lines
Abstract
The question, which heating mechanism is responsible for the heating of the transition layers and stellar coronae. is still an open one. We have now developed a theory for stellar transition layers which are homogeneous. at least in sectors. which does permit to determine from the observed emission measures the amount of mechanical energy input in the lower transition layer and determine the boundary condition Pe(T) for the upper transition layer. The mechanical flux and the damping length for this flux for the upper part of the transition layer can be determined from the emission measures in the upper transition zone and from the coronal temperature. or, if no emission measures for the upper transition zone are available the emission measure determined from the coronal X-ray emission can be used instead. though less reliably. Using this method we found that the lower transition layers of the sun and Procyon are probably heated by shock wave heating. The upper transition layer of Procyon also seems to be heated by shock waves. while in the sun in the upper part of the transition layer the damping length is too long to be consistent with shock wave heating. We want to study whether and where in the late F star region a transition from shock wave heating to MHD wave heating of the upper transition layer occurs.
- Publication:
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IUE Proposal
- Pub Date:
- 1988
- Bibcode:
- 1988iue..prop.3048B