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J. T. Karpen (NRL), S. E. M. Tanner (George Mason U.), S. K. Antiochos, C. R. DeVore (NRL)
We have shown, over the past few years, that both static and dynamic prominence condensations can be formed through steady but unequal localized heating in long coronal loops (Antiochos et al. 1999, 2000; Karpen et al. 2001, 2003). Theoretical analyses and numerical simulations with ARGOS, our 1D hydrodynamic code with adaptive mesh refinement, have revealed the behavior of this thermal nonequilibrium mechanism under a wide range of solar conditions. Previously we identified several key parameters governing the existence and characteristics of the condensations: the ratio of loop length to heating scale, the loop apex height, the heating imbalance, and (for dipped fieldlines only) the dip slopes. These earlier calculations assumed a constant cross-sectional area throughout the flux tube, but on the Sun we expect the areas to be highly nonuniform.
To test this condensation process under more realistic conditions, we used our sheared 3D arcade model of the prominence magnetic field (DeVore & Antiochos 2000) to define the geometry of the model flux tube in a set of calculations with ARGOS. We selected representative field lines capable of supporting condensations from the DeVore & Antiochos 3D MHD simulation, measured the flux tube area at intervals along these lines, and derived 5th order polynomial fits to the height and area that were easily recomputed upon regridding. For comparison, constant cross-section ``control" loops also were set up with the same height variations. These field lines were subjected to localized heating near the footpoints, as before, and subsequent developments were monitored. We have explored the effects of uniform vs. nonuniform area, changing the heating imbalance, and altering the radiative loss function. Results from this study will be compared with our previous work and with prominence observations.
This work was supported by NASA and ONR.
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Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.