Impulsively heated solar coronal plasma

Mendoza-Briceno, C. A. (2005) Impulsively heated solar coronal plasma. In: British-Romanian-Hungarian N+N+N Workshop for Young Researchers On Plasma- and Astrophysics: from laboratory to outer space Edited by I. Ballai, E. Forgács-Dajka, A. Marcu and K. Petrovay. Publications of the Astronomy Department of the Eötvös University (15). ELTE Sokszorosítóüzeme, Budapest, pp. 35-44.

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Abstract

The dynamics response of the solar coronal plasma in a magnetic flux tube undergoing impulsive heating through the release of localized Gaussian energy pulses near the loop's footpoints is investigated. It was found that when a discrete number of randomly spaced pulses is released, loops heat up and stay at coronal temperatures for the whole duration of the impulsive heating stage provided that the elapsing time between pulses is less than a critical one. For elapsing times longer than this critical value, coronal temperatures can no longer be maintained and the loop apex cools down reaching chromospheric temperatures. For a large number of pulses having a fully random spatio-temporal distribution, the variation of the temperature along the loop is highly sensitive to the spatial distribution of the heating. As long as the heating concentrates more and more at the loop's footpoints, the temperature variation is seen to make a transition from that of a uniformly heated loop to a flat, isothermal profile along the loop length. Concentration of the heating at the footpoints also results in a more frequent appearance of rapid and significant depressions of the apex temperature during the loop evolution, most of them ranging from ~1.5×10^6 to ~10^4 K and lasting from about 3 to 10 minutes. This behavior strongly resembles the intermittent variability of coronal loops inferred from SoHO observations in active regions of the solar atmosphere.

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