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Astron. Astrophys. 349, 974-984 (1999)


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The energy balance in solar prominences

U. Anzer 1 and P. Heinzel 2,1

1 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, D-85740 Garching, Germany
2 Astronomical Institute, Academy of Sciences of the Czech Republic, CZ-25165 Ondejov, Czech Republic

Received 18 June 1999 / Accepted 3 August 1999

Abstract

In this paper we study the energy balance in quiescent solar prominences. For this investigation we use a simple 1D slab model in magneto-hydrostatic equilibrium. We divide the studied region into two parts:

The inner region consisting of the prominence itself and the cool part of the transition region (up to 30000 K). In this region the plasma is optically thick in several atomic transitions and therefore we have to solve the non-LTE radiative transfer problem in this part. This allows us to derive self-consistently the gas density, the ionization degree of hydrogen and the hydrogenic radiation losses. The energy transport by thermal conduction can be neglected in this region.

In the outer part of the transition region, the thermal conduction becomes very important but the treatment of radiation is simplified by the fact that the plasma is optically thin.

We find that energy balance in prominences can only be obtained for special forms of the heating function. This requirement is very stringent for the inner parts, while in the outer region thermal conduction can transport large amounts of the heat energy and therefore a wider class of heating functions will be allowed.

Key words: Magnetohydrodynamics (MHD) – radiative transfer – Sun: prominences – Sun: transition region

Send offprint requests to: U. Anzer (ula@mpa-garching.mpg.de)

© European Southern Observatory (ESO) 1999

Online publication: September 13, 1999

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