Lecturer:
Christoph Kuckein
Leibniz-Institut für Astrophysik Potsdam (AIP)
An der Sternwarte 16, 14482 Potsdam
Germany

Title:
Solar flares: a case study of the 2013 May 17 flare

Abstract:
Solar flares are among the most energetic events in the solar system.
Such a process involves the whole electromagnetic spectrum. Flares are
classified with letters A, B, C, M or X according to the peak flux in
the wavelength bands between 1-8 Å x-rays as measured by the
Geostationary Operational Environmental Satellite system (GOES). The
most energetic flares are of type X, followed by M-class flares. In
order to understand the complex triggering process of flares,
simultaneous multiwavelength observations to link different heights of
the solar atmosphere are getting more and more important. However, the
unpredictability of flares makes them extremely hard to observe with
high resolution ground-based telescopes.
In this talk I will present a special data set of an M-class flare
observed on 2013 May 17 with multiple instruments and wavelengths during
an observing campaign at the Vacuum Tower Telescope (VTT) at
Observatorio del Teide, Tenerife, Spain. Several hours of observations
covered the entire flare, including the pre-flare, impulsive,
relaxation, and post-flare phases. Spectropolarimetric measurements of
the four Stokes parameters in the upper chromosphere (He I triplet at
10830 Å) and in the underlying photosphere (Si I line at 10827 Å)
allows to study the dynamics and infer information about the magnetic
field during different stages of the flare. The analysis of all the data
is still ongoing. I will report on what we have learned (so far).