H. Peter, S. Bingert, S. Kamio
Condensations in the more than 10^6 K hot corona of the Sun are commonly
observed in the extreme ultraviolet (EUV). While their contribution to the
total solar EUV radiation is still a matter of debate, these condensations
certainly provide a valuable tool for studying the dynamic response of the
corona to the heating processes. We investigate different distributions of
energy input in time and space to investigate which process is most relevant
for understanding these coronal condensations. For a comparison to observations
we synthesize EUV emission from a time-dependent, one-dimensional model for
coronal loops, where we employ two heating scenarios: simply shutting down the
heating and a model where the heating is very concentrated at the loop
footpoints, while keeping the total heat input constant. The heating off/on
model does not lead to significant EUV count rates that one observes with
SDO/AIA. In contrast, the concentration of the heating near the footpoints
leads to thermal non-equilibrium near the loop top resulting in the well-known
catastrophic cooling. This process gives a good match to observations of
coronal condensations. This shows that the corona needs a steady supply of
energy to support the coronal plasma, even during coronal condensations.
Otherwise the corona would drain very fast, too fast to even form a
condensation.
View original:
http://arxiv.org/abs/1112.3667
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