Modeling Evolving Coronal Loops with Observations from STEREO, Hinode, and TRACE

Abstract

The high densities, long lifetimes, and narrow emission measure distributions observed in coronal loops with apex temperatures near 1 MK are difficult to reconcile with physical models of the solar atmosphere. It has been proposed that the observed loops are actually composed of sub-resolution ``threads'' that have been heated impulsively and are cooling. We apply this heating scenario to nearly simultaneous observations of an evolving post-flare loop arcade observed with the EUVI/\textit{STEREO}, XRT/\textit{Hinode}, and \textit{TRACE} imagers and the EIS spectrometer on \textit{HINODE}. We find that it is possible to reproduce the extended loop lifetime, high electron density, and the narrow differential emission measure with a multi-thread hydrodynamic model provided that the time scale for the energy release is sufficiently short. The model, however, does not reproduce the evolution of the very high temperature emission observed with XRT. In XRT the emission appears diffuse and it may be that this discrepancy is simply due to the difficulty of isolating individual loops at these temperatures. This discrepancy may also reflect fundamental problems with our understanding of post-reconnection dynamics during the conductive cooling phase of loop evolution.

Revised version submitted to ApJ in response to referee's comments

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• MHD modeling of coronal loops: the transition region throat
• Geometric Assumptions in Hydrodynamic Modeling of Coronal and Flaring Loops
• 2D MHD and 1D HD models of a solar flare -- a comprehensive comparison of the results
• The Role of Magnetic Topology in the Heating of Active Region Coronal Loops
• Transition region contribution to AIA observations in the context of coronal heating
• EUV Analysis of a Quasi-Static Coronal Loop Structure