Timothy Duckenfield

It is clear that the solar corona is maintained at (apparent) thermal equilibrium by a delicate balance between radiative losses and some unknown heating mechanism. It is also clear that the effect of these heating and cooling mechanisms varies with the plasma parameters, such as density and temperature. Slow magnetoacoustic waves - which are common in the corona - are able to perturb these heating and cooling mechanisms enough to be themselves affected in a measurable way. An interesting avenue of research is therefore using these slow waves as probes of the local thermal equilibrium, since by measuring their properties through observations we may infer some information about the enigmatic coronal heating function.
This research direction, considering the effect of heating/cooling misbalance upon slow waves, has received renewed attention in recent years. In this talk I will summarise recent progress, with a focus on the effect of the magnetic field. Crucially I will show that for a sufficiently strong magnetic strength, the slow wave dynamics is insensitive to any dependence of the heating function on the magnetic field. This approximation is found to be valid in the corona so long as the magnetic field strength is greater than approximately 10G for quiescent loops and plumes, and 100G for hot and dense loops. Finally, I will discuss the implications of this result for the seismological inference of the coronal heating function via slow waves.