Coronal magnetic field and the plasma beta determined from radio and multiple satellite observations

TL;DR

This study combines radio and EUV satellite observations to derive the coronal magnetic field, plasma density, and plasma beta in post-flare loops, providing insights into coronal plasma conditions.

Contribution

It introduces a method to simultaneously determine coronal magnetic fields and plasma parameters using radio and EUV data, enhancing understanding of coronal plasma beta.

Findings

Derived magnetic field from radio polarization data.

Estimated plasma beta around 5.7×10^(-4) to 7.6×10^(-4).

Identified discrepancies between radio and EUV density estimates.

Abstract

We derived the coronal magnetic field, plasma density, and temperature from the observation of polarization and intensity of radio thermal free-free emission using the Nobeyama Radioheliograph (NoRH) and extreme ultraviolet (EUV) observations. We observed a post-flare loop on the west limb 11 April 2013. The line-of-sight magnetic field was derived from the circularly polarized free-free emission observed by NoRH. The emission measure and temperature were derived from the Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO). The derived temperature was used to estimate the emission measure from the NoRH radio free-free emission observations. The derived density from NoRH was larger than that determined using AIA, which can be explained by the fact that the low temperature plasma is not within the temperature coverage of the AIA filters used in this study. We also discuss the other observation of the post-flare loops by the EUV Imager onboard the Solar Terrestrial Relations Observatory (STEREO), which can be used in future studies to reconstruct the coronal magnetic field strength. The derived plasma parameters and magnetic field were used to derive the plasma beta, which is a ratio between the magnetic pressure and the plasma pressure. The derived plasma beta is about 5.7*10^(-4) to 7.6*10^(-4) at the loop top region.