The heating of the solar plasma due to microwave phenomena correlated with type II meter bursts |
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| Authors: | E Fürst |
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| Institution: | (1) Max-Planck-Institut für Radioastronomie, Bonn, Germany |
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| Abstract: | The heating of the solar plasma of those layers is considered where the microwave bursts are emitted. In a first step, we restrict ourselves to phenomena correlated with the so-called type II m bursts. Bursts of this kind are excited by shock-waves initiated near the optical flare region. These shock-waves spread out into the higher corona, and if the shock strength is sufficiently high, the microwave region is heated to 107 K. But this temperature is too low to explain the burst radiation. In this paper, it is shown that at plasma temperatures about 107 K a fairly high number of electrons is accelerated by Alfvén waves to equivalent kinetic temperatures of about 108 K. We assume that the Alfvén waves are generated near the sunspots, and, therefore, the accelerated electrons run along the magnetic-field lines into the microwave source lying between the two spots of an assumed dipole field. Within this source, the considered electrons thermalize and, after a short time, the source reaches temperatures of 5 × 107 K to 108 K.A plasma of this temperature with an electron density about 5 × 109 cm–3 and a magnetic induction of 300 G is optically thick even at frequencies about 10 GHz, because the gyromagnetic absorption is very high. |
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