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Detection of ultra-long-period oscillations in an EUV filament \ud

By C. (Claire) Foullon, E. (Erwin) Verwichte and V. M. (Valery M.) Nakariakov


We report the first detection of long-period (8-27 h) oscillatory intensity variations in a coronal filament. The filament is observed continuously as it crosses the solar disk in a 12-min-cadence SoHO/EIT 195 Å uninterrupted data set. Cyclic intensity variations are found to be correlated along the filament, while the most pronounced oscillations are detected at its southern end for nearly 6 days. The dominant period of these oscillations is 12.1 h and the amplitude of the intensity variations reaches approximately 10% of the background intensity. The ultra-long-period oscillations may be interpreted in terms of slow string MHD modes or may be connected with thermal over-stability associated with peculiarities of the cooling/heating function and with the effect of neutrals. These theoretical predictions however do not explain the spatial structure of the oscillations along the filament

Topics: QB
Publisher: EDP Sciences
Year: 2004
OAI identifier: oai:wrap.warwick.ac.uk:3798

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