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Astron. Astrophys. 321, 921-926 (1997)

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Problems in measuring prominence oscillations

P. Sütterlin 1, E. Wiehr 1, M. Bianda 2 and G. Küveler 3

1 Universitäts-Sternwarte, Geismarlandstr.11, D-37083 Göttingen, Germany
2 Istituto Ricerche Solari Locarno, Via Patocchi, CH-6644 Orselina, Switzerland
3 Fachhochschule Wiesbaden, Am Brückweg 26, D-63547 Rüsselsheim, Germany

Received 12 September 1996 / Accepted 29 October 1996


Time variations of Doppler shifts of the Ca [FORMULA] 8542  Å emission in quiescent solar prominences have been measured. A new type of 'limb guider' assures a highly constant distance of the spectrograph slit from the solar limb and furthermore removes low frequency image motion in the direction perpendicular to the slit.

Remaining image motion along the slit is usually removed by a correlation of subsequent spectra. This procedure, however, cannot be applied globally to the whole spatial height in the spectra if individual structures exhibit lateral motions along the slit or even decay or arise during the observation. We therefore correlate defined individual emission maxima from successive spectra.

The finally obtained power spectra show oscillations with a variety of periods at restricted locations. The data favour the known general presence of periods near 20 and 60 min, however they give only slight indication for 'typical' periods near 3 and 5 min.

Key words: Sun: prominences; oscillations

Send offprint requests to: E. Wiehr

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998