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Overshooting Motions from the Convection Zone and their Role in Atmospheric Heating

Published online by Cambridge University Press:  30 March 2016

Juri Toomre
Juri Toomre*
Affiliation:
Department of Astro-Geophysics and, Joint Institute for Laboratory Astrophysics, University of Coloradoand National Bureau of Standards, Boulder, CO 80309, U.S.A.

Extract

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Chromospheres and coronae in stars appear to require vigorous convection zones just below the surface. If we wish to understand how various dynamical instabilities contribute to the mechanical heating that is required to produce chromospheres, then we must be concerned both with fluid motions in the atmosphere and with the nature of their driving below the surface. One cannot really separate these two subjects. In order to emphasize this link, we will raise some basic questions about convective flows in a stellar envelope and of their penetration into the atmosphere. The significant puzzles between what is observed and what can be theoretically explained should serve to indicate some of the issues that need to be pursued. We will concentrate on the Sun in our discussions: the observations here are sufficiently detailed to provide the explicit challenges to theory unavailable in most other stars. However, we will also turn to A-type stars to illustrate a theoretical procedure for describing convection that may do better than the mixing-length approach in predicting the vertical structure in these flows.

Type
Joint Discussion
Information
Highlights of Astronomy , Volume 5: Highlights of Astronomy. As presented at the XVIIth General Assembly of the IAU, 1979 , 1980 , pp. 571 - 580
Copyright
Copyright © Cambridge University Press 1980

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