General Physics Physics Seminar Tuesday 8 October 2002


TRACE observations of longitudinal waves in coronal loops

Ineke de Moortel

School of Mathematics and Statistics, University of St.Andrews, North Haugh, St.Andrews, Scotland



High cadence TRACE (Transition Region And Coronal Explorer) observations show that outward propagating intensity disturbances are a common feature in large, quiescent coronal loops.

An overview is given of measured parameters of such longitudinal waves in coronal loops, where a wavelet analysis is used to estimate the oscillatory periods. We found that loops that are situated above sunspot regions display intensity oscillations with periods centred around 3 minutes, whereas oscillations in `non-sunspot' loops show periods centred around 5 minutes.

The observed propagating intensity disturbances are interpreted as propagating slow magnetoacoustic waves and we show that the disturbances are not flare-driven but are most likely caused by an underlying driver exciting the loop footpoints. We found that (slightly enhanced) thermal conduction could account for the observed damping lengths.