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Astron. Astrophys. 347, 355-365 (1999)

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A wavelet analysis of active region oscillations

J. Ireland 1,2, R.W. Walsh 2, R.A. Harrison 3 and E.R. Priest 2

1 NASA Goddard Space Flight Center, Room G-1, Building 26, Mail Code 682.3, Greenbelt, Maryland 20771, USA
2 School of Mathematical and Computational Sciences, University of St. Andrews, St. Andrews, KY16 9SS, UK
3 Space Science Department, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, UK

Received 24 February 1999 / Accepted 21 April 1999


The wavelet transform is applied to the analysis of active region oscillations. The localised (in time) nature of the wavelet transform allows us to study both the duration of any statistically significant oscillations as well as their period. Time series arising from SOHO (Solar and Heliospheric Observatory) CDS-NIS (Coronal Diagnostic Spectrometer Normal Incidence Spectrometer) active region observations on 14th-15th November 1996 are used to demonstrate the applicability of wavelet methods. High cadence (approximately 14 seconds) observations were made in He I 584.33 Å ([FORMULA]), O V 629.73 Å ([FORMULA]), Mg IX 368.06 Å ([FORMULA]), Fe XVI 360.76 Å ([FORMULA]) provide detailed intensity information on the active region over a wide range of temperatures. The distribution of statistically significant periods found varies from line to line, as does their duration.

Key words: Sun: chromosphere – Sun: corona – Sun: oscillations – Sun: transition region – Sun: UV radiation

Send offprint requests to: J. Ireland (ireland@esa.nascom.nasa.gov)

© European Southern Observatory (ESO) 1999

Online publication: June 18, 1999