Computer Science
Scientific paper
Jan 2004
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004esasp.547...45b&link_type=abstract
Proceedings of 'SOHO 13 - Waves, Oscillations and Small-Scale Transient Events in the Solar Atmosphere: A Joint View from SOHO a
Computer Science
3
Sunspot, Oscillation, Ultraviolet
Scientific paper
Oscillations above thirteen sunspots are investigated with the Coronal Diagnostic Spectrometer (CDS) and the Transition Region And Coronal Explorer (TRACE). The CDS observations give knowledge about the oscillations in the chromosphere, transition region, and corona and information regarding the contributions of different emission lines to the TRACE 171 Å and 195 Å channel intensities. A period close to 3 min is observed above the umbra of each sunspot. The observations give support to the idea that the 3 min oscillations are caused by upwardly propagating acoustic waves. This is evident from the asymmetry of the oscillation amplitudes in the red and blue wings of the emission lines, where the oscillations are decidedly more pronounced in the blue than in the red line wing. Additional support for the acoustic wave hypothesis emerges from the agreement between the observed and predicted relations in phase and magnitude between the oscillations in intensity and line-ofsight velocity. The frequency of the oscillations is above the acoustic cutoff frequency in the umbral atmosphere and the observed phase differences between lines emitting at different temperatures point to an upwardly propagating disturbance.
Brynildsen Nils
Fredvik T.
Kjeldseth-Moe Olav
Maltby Per
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