Title : Time variability of the Evershed effect

Author : L.H.M. Rouppe van der Voort

To appear in the poster proceedings of the First Potsdam Thinkshop on
Sunspots & Starspots, May 6-10, 2002

abstract :

  The time variability of the Evershed effect in the penumbra of a
  sunspot is studied from a series of high-spatial-resolution
  spectrograms obtained with the Swedish Vacuum Solar Telescope on La
  Palma.  Photospheric reference images from the Dutch Open Telescope
  were used to study the solar scene around the region covered by the
  spectrograph slit.  From a comparison of two 1-hour velocity
  profiles, one with significant Evershed signal and one without, it
  is found that the Evershed effect varies on a typical time scale of
  more than 10 minutes.