Volume 410, Number 1, October IV 2003
|Page(s)||315 - 321|
|Published online||17 November 2003|
Observations of oscillations in the transition region above sunspots
Astrophysical Institute Potsdam (AIP), Sonnenobservatorium Einsteinturm, Telegrafenberg, 14473 Potsdam, Germany
2 Max-Planck-Institut für Aeronomie, 37191 Katlenburg-Lindau, Germany e-mail: firstname.lastname@example.org
Corresponding author: J. Rendtel, email@example.com
Accepted: 29 July 2003
Observations during two campaigns of the SUMER spectrograph and the EIT imager onboard SoHO were used to analyse oscillations in bright sunspot plumes. We report variations of both intensity and velocity seen in EUV emission lines originating in the sunspot upper chromosphere and the transition region. The wavelet analysis reveals rapidly changing conditions in the emitting volumes. Generally, oscillations in the 5 min range dominate in the chromosphere, while the transition region lines show oscillations at shorter periods (2 to 3 min). A drift of the oscillation period of the Doppler velocity from to within about 30 min can be explained by a strongly non-stationary behaviour of the upper chromosphere and transition region, probably related to downstream of material within the plume region. Synchronous EIT observations of the lower corona show no intensity oscillations. This hints either at a strong damping or a downward reflection in the upper transition region or lower corona.
Key words: Sun: chromosphere / Sun: transition region / Sun: oscillations / sunspots
© ESO, 2003
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.