Rouppe van der Voort, Luc

Contact Email: rouppe@astro.su.se
Institute: Royal Swedish Academy of Sciences
Research URL:http://www.astro.su.se/~rouppe
Presenting Thesis: Yes
Subject Area: The Sun
Waveband: Ultraviolet
Technique: Imaging (Direct), Spectroscopy
Presentation: Poster Dsiplay
Title: Observations of umbral flashes
Abstract: The chromosphere of the umbra of sunspots displays a very dynamic behavior when observed in the Calcium H and K lines. With a typical period of 2-3 minutes parts of the umbra brighten dramatically for short duration. These brightenings, related to chromospheric umbral oscillations, are typical for observations in the H and K lines and are called umbral flashes. Observations of sunspots recorded at the Swedish Vacuum Solar Telescope (SVST) and the Dutch Open Telescope (DOT) at La Palma are presented. The spectral evolution of the Ca II K core is shown. Movies and time slices of the images suggest a relation between umbral flashes and running penumbral waves. Running waves, coherent over a large fraction of the penumbra, seem to be excited by flashes that occur close to the umbra-penumbral boundary.