Geometric Assumptions in Hydrodynamic Modeling of Coronal and Flaring Loops

Abstract In coronal loop modeling, it is commonly assumed that the loops are semicircular with a uniform cross-sectional area. However, observed rarely semicircular, and extrapolations of magnetic field show strength decreases height, implying area expands height. We examine these two assumptions directly, to understand how they affect hydrodynamic radiative response short, hot strong, impulsive electron beam heating events. Both magnitude rate expansion impact dynamics an expanding cross section significantly lengthens time for cool drain, increases upflow durations, suppresses sound waves. The standard T ∼ n 2 relation cooling does not hold loops, which relatively little draining. An increase in eccentricity on other hand, only draining timescale, minor effect general. Spectral line intensities also strongly impacted by variation because depend both volume emitting region as well density ionization state. With larger expansion, reduced, so lines at all heights reduced intensity, times, hottest remain bright longer. Area critical accurate modeling hydrodynamics radiation, observations needed constrain magnitude, rate, location expansion—or lack thereof.