Discrete random heating events in coronal loops

The response of the coronal plasma in a magnetic loop to the release of discrete, random amounts of energy quanta over fixed time intervals is investigated. Nanoflare heating (10(24) erg per event) with event lifetimes on a scale of 1-20 s are shown to be able to maintain a coronal loop at typical coronal temperatures, approximate to 2 x 10(6) K (Parker, 1988; Kopp and Poletto, 1993). Microflare events (10(27) erg) observed by Porter et al. (1995) with a lifetime of approximately 1 min are also investigated and it is found that the loop apex temperature varies by at most 40% from its initial static condition. However, larger energy events of the order of 10(28) erg (Schmieder et al., 1994) occur too infrequently and the plasma cools to chromospheric values. The implications of time-dependent heating of the corona upon observations are also discussed.