Modeling of the Extreme-Ultraviolet and Soft X-Ray Emission in a Solar Coronal Bright Point

Abstract

Previous studies have been able to reproduce both the observed intensities and the morphology of high-temperature solar plasma using steady state heating models. These models, however, have been unable to reproduce the lower temperature emission observed in active regions. Here we present results from numerical simulations of a coronal bright point. We use potential field extrapolations of a Kitt Peak magnetogram to compute the coronal field lines and populate them with solutions to the hydrostatic loop equations based on a volumetric heating function that scales as bar B/L, where bar B is the magnetic field strength averaged along a field line and L is the loop length. We consider the effects of altering the magnitude and scale height of the energy deposition and the effect of allowing the loop cross sections to expand proportionally to 1/bar B. We then use the computed densities and temperatures to calculate average intensities and simulated EUV and soft X-ray images and compared them to Yohkoh and SOHO observations. We find that our best-case model (apex heating of expanding loops) can reproduce the high-temperature emission, the general morphology of the lower temperature emission, and the majority of the average intensities of reliable lines over a wide range of temperatures to within ~20%. The morphology in the EUV visualizations, however, shows some differences from the observations. These results suggest the role of nonpotential or evolving magnetic fields, or dynamic processes, but indicate that departures from the potential field hydrostatic case may not be too large.