Electron density and temperature structure of two limb active regions observed by SOHO-CDS

Abstract

The analysis of two active regions on the limb using observations from SOHO-CDS allows us to determine the electron density and temperature distribution of the coronal emission. We find that the active regions have hot cores (3×10⁶ K) with larger cooler (10⁶ K) loop structures extending above the limb. The electron number density, determined using the Si X diagnostic line ratio, is found to be highest in the active region core (greater than 2.3×10⁹ cm⁻³). Electron number density values are determined for a range of spectral lines from different ions and are found to increase with temperature between 0.8 and 2.5×10⁶ K. These results are consistent with recent models of enhanced heating along the compact core of active regions, where the magnetic field shear is strongest.