M. Luna, J. T. Karpen, C. R. DeVore
We investigate the process of formation and subsequent evolution of
prominence plasma in a filament channel and its overlying arcade. We construct
a three-dimensional time-dependent model of an intermediate quiescent
prominence. We combine the magnetic field structure with one-dimensional
independent simulations of many flux tubes, of a three-dimensional sheared
double arcade, in which the thermal nonequilibrium process governs the plasma
evolution. We have found that the condensations in the corona can be divided
into two populations: threads and blobs. Threads are massive condensations that
linger in the field line dips. Blobs are ubiquitous small condensations that
are produced throughout the filament and overlying arcade magnetic structure,
and rapidly fall to the chromosphere. The threads are the principal
contributors to the total mass. The total prominence mass is in agreement with
observations, assuming a reasonable filling factor. The motion of the threads
is basically horizontal, while blobs move in all directions along the field.
The peak velocities for both populations are comparable. We have generated
synthetic images of the whole structure in an H$\alpha$ proxy and in two EUV
channels of the AIA instrument aboard SDO, thus showing the plasma at cool,
warm, and hot temperatures. The predicted differential emission measure of our
system agrees very well with observations. We conclude that the sheared-arcade
magnetic structure and plasma behavior driven by thermal nonequilibrium fit
well the abundant observational evidence for typical intermediate prominences.
View original:
http://arxiv.org/abs/1201.3559
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