The solar corona as an active medium for magnetoacoustic waves

Abstract The presence and interplay of continuous cooling heating processes maintaining the corona Sun at observed one million K temperature were recently understood to have crucial effects on dynamics stability magnetoacoustic (MA) waves. These essentially compressive waves perturb coronal thermal equilibrium, leading phenomenon a wave-induced misbalance (TM). Representing an additional natural mechanism for exchange energy between plasma wave, TM makes active medium MA waves, so that wave can not only lose but also gain from source (similarly burning gases, lasers masers). We review recent achievements in this newly emerging research field, focussing slow-mode experience as back-reaction perturbed equilibrium. new include enhanced frequency-dependent damping or amplification slow effective, associated with non-uniformity, dispersion. discuss possibility probe unknown function by observations linear theory instabilities. manifold properties acquire thermodynamically nature solar indicate clear need accounting combined heating/cooling traditional problems formation evolution prominences rain, adequate modelling interpretation magnetohydrodynamic