Validation of MHD Model Predictions of the Corona with LASCO-C2 Polarized Brightness Images

Abstract

Progress in our understanding of the solar corona requires that the results of advanced magnetohydrodynamic models driven by measured magnetic fields, and particularly the underlying heating models, be thoroughly compared with coronal observations. The comparison has so far mainly concerned the global morphology of the corona, synthetic images calculated from the models being compared with observed images. We go one step further by performing detailed quantitative comparisons between the calculated polarized radiance $pB$ using the three-dimensional electron density produced by MHD models and well calibrated polarized images obtained by the Large Angle Spectrometric Coronagraph LASCO-C2 coronagraph complemented by ground-based images when available from the Mauna Loa Solar Observatory Mark IV and K-Cor instruments to extend the comparison to the inner coronal region 1.0 – 2.5 $\mbox{R}_{\odot }$, which is inaccessible to C2. We take advantage of the high-resolution and high-quality MHD predictions performed for several solar eclipses (1 August 2008, 11 July 2010, 13 November 2012, and 21 August 2017) and for the first perihelion passage of the Parker Solar Probe (5 November 2018) using two different three-dimensional MHD models relying on either a thermodynamic or a wave-turbulence-driven methodologies to heat the corona. Both models are generally able to match the observed structure and photometry of the corona albeit with various degrees of fidelity for which there is no obvious explanation. However, two limitations emerge, the complexity of coronae of the maximum type and the time lapse between the completion of the magnetograph measurements and the prediction.