Proc. of 'The 13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun' Hamburg, Germany (ESA SP-560, February 2005), 1035-1038

(workshop hold July 5-9, 2004 in Hamburg, Germany)

Sven Wedemeyer-Böhm (Kiepenheuer-Institut f. Sonnenphysik, D-79104 Freiburg, Germany),
Hans-Günter Ludwig (Lund Observatory, Lund, Sweden),
Matthias Steffen (Astrophysikalisches Institut Potsdam, D-14482 Potsdam, Germany),
Bernd Freytag (Astronomical Observatory, University of Uppsala, Sweden),
Hartmut Holweger (Institut für Theoretische Physik und Astrophysik, Universität Kiel, D-24098 Kiel, Germany),

The shock-patterned solar chromosphere in the light of ALMA

Recent three-dimensional radiation hydrodynamic simulations by Wedemeyer et al. (2004) suggest that the solar chromosphere is highly structured in space and time on scales of only 1000 km and 20-25 sec, resp.. The resulting pattern consists of a network of hot gas and enclosed cool regions which are due to the propagation and interaction of shock fronts. In contrast to many other diagnostics, the radio continuum at millimeter wavelengths is formed in LTE, and provides a rather direct measure of the thermal structure. It thus facilitates the comparison between numerical model and observation. While the involved time and length scales are not accessible with todays equipment for that wavelength range, the next generation of instruments, such as the Atacama Large Millimeter Array (ALMA), will provide a big step towards the required resolution. Here we present results of radiative transfer calculations at mm and sub-mm wavelengths with emphasis on spatial and temporal resolution which are crucial for the ongoing discussion about the chromospheric temperature structure.

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