Microflares and loop oscillations

Microflares are small A to C class X-ray brightenings that occur at a rate of about 10 per hour in an average active region (Shimizu et al., 1992). They show signatures of non-thermal emission in RHESSI X-ray spectra and are seen as an important link between large-scale flares and the intangible nanoflares that have been proposed as the energy source for the active region corona. In this contribution we analyze microflare loop brightenings seen in the Fe XIX line with SUMER. For the two active regions studied, we find an Fe XIX loop brightening rate significantly higher than soft X-ray microflares. Almost half the events have Fe XIX Doppler shift oscillations. We summarize the basic characteristics of the oscillations and discuss their importance in the context of models of microflare loop excitation.