Coronal heating by Alfvén waves,II |
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| Authors: | Donat G Wentzel |
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| Institution: | (1) High Altitude Observatory, National Center for Atmospheric Research, 80303 Boulder, Colorado, U.S.A.;(2) Present address: Astronomy Program, University of Maryland, 20742 College Park, MD, U.S.A. |
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| Abstract: | I extend a previous paper which argued that Alfvén waves traveling up a large coronal loop may heat this loop at the top and increase its visibility. This heating is now evaluated more completely, taking into account the changes along the loop in field strength, gas density and flux of waves. The location and efficiency of the heating depend very non-linearly on the intensity of the waves, which allows rapid changes in the visibility of a loop. Observational and theoretical conditions for the applicability of the theory are summarized. Alfvén waves preferentially heat the upper portions of coronal helmets, but a measurable excess temperature on a loop requires somewhat implausibly high wave fluxes. Radiation losses from low-lying loops with strong magnetic fields cannot be explained without modifying the theory.The National Center for Atmospheric Research is sponsored by the National Science Foundation. |
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