Necessary Conditions for a Hot Quiet Sun Atmosphere: Chromospheric Flares and Low Corona Twisted Flux Rope Eruptions
Résumé
The issue of relevant scales involved in the heating of the solar atmosphere is an important one. Since the temperature already reaches 1 MK a few megameters above the photosphere, observations made by Parker Solar Probe will be able to explore those at larger heights but only indirectly at those lower heights, where small scale coupling between sub-photospheric, chromospheric and coronal structure and dynamics occurs. While Solar Orbiter will be able to bring such observations, modeling appears a complementary interesting approach to interpret those observations Taking a sub-surface dynamo and a sharp realistic VAL- like scale profile from photosphere to corona, with a fixed temperature profile in time, we investigate the necessary conditions implied on the structures and dynamics of the atmosphere to keep this thermal structuration, as well as their implication in the energy budget of the atmosphere. Under those hypothesis we show that :i) the transverse photospheric field below 100km plays a major role; ii) an associated scale of one megameter activity naturally results to produce a zone above the photosphere with high confined electric currents, which then expands into the chromosphere and releases energy(4 500 W/m2) through small-scale eruptions driving sonic motions; iii) meso scale structuration, leads to the formation of larger coherent twisted flux ropes, and associated eruptive like activity in a way similar to large scale eruptive phenomena, as result of cancellation, emergence, and convergence motions. Finally a wave dynamics is also naturally driven in core corona associated to above 300 W/m2.