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Session 5 - SOHO Corona III.
Oral session, Friday, June 27
Ballroom A, Chair: John Mariska
The physical nature of coronal heating remains one of the great problems of solar physics. One of the several theories that are being pursued is the resonant absorption of MHD waves. While promising in several respects, this theory has suffered from a glaring deficiency: the computed heating is incompatible with both the assumed density and the observed structure of coronal loops.
We present the first model of resonant heating of coronal loops that incorporates the dependence of the loop density on the heating rate. By adopting the quasi-static equilibrium scaling law \rho\propto Q^5/7, where \rho is the density and Q is the volumetric heating rate, we are able to approximate the well-known phenomena of chromospheric evaporation and chromospheric condensation, which regulate the coronal density. We combine this scaling law with a linearized MHD model for the resonant absorption of Alfvén waves to study the spatial and temporal dependence of the heating. We find that the heating is concentrated in multiple resonance layers, rather than the single layer of previous models, and that these layers drift throughout the loop to heat the entire volume. These new properties are in much better agreement with coronal observations, including recent observations from the CDS and EIT instruments on SOHO, as well as earlier observations from the SXT instrument on Yohkoh.
Program listing for Friday