Quiet-Sun coronal loops: Models and Coronal Heating Implications

MANDRINI, C.H.; MAC CORMACK, C.; LÓPEZ FUENTES, M.C.; LLOVERAS, D.G.; VÁSQUEZ, A.M.

Busan

Congreso; IAU XXXIst General Assembly; 2022

The structure of the solar corona is made of magnetic flux tubes or loops. Due to the lack of contrast with theirenvironment, observing and studying coronal loops in the quiet Sun is extremely difficult. We use a differentialemission measure tomographic (DEMT) technique to reconstruct, from a series of EUV images covering anentire solar rotation, the average 3D distribution of the thermal properties of the coronal plasma. By combiningthe DEMT products with extrapolations of the global coronal magnetic field, we reconstruct coronal loops andobtain the energy input required to keep them at the typical million-degree temperatures of the corona. Westatistically study a large number of reconstructed loops for Carrington rotation (CR) 2082 obtaining a series oftypical average loops of different lengths. We look for relations between the thermal properties and the lengthsof the constructed typical loops and find similar results to those found in a previous work. We analyze the typicalloop properties by comparing them with the zero-dimensional (0D) hydrodynamic model Enthalpy-BasedThermal Evolution of Loops (EBTEL). We explore two heating scenarios. In the first one, we apply a constantheating rate assuming that typical loops are in quasi-static equilibrium. In the second scenario we heat theplasma in the loops using short impulsive events. We find that the reconstructed typical loops are “overdense”with respect to quasi-static equilibrium solutions. Impulsive heating, on the other hand, reproduces betterthe observed densities and temperatures for the shorter and approximately semicircular loops. We suggestthat to properly assess the physical characteristics of the analyzed loops, it would be necessary to use a moresophisticated model with which to study loop temperature and density profiles and test localized heating atdifferent locations.KEYWORDS Sun: Corona, Sun: Magnetic field, Sun: Quiet, Sun: Coronal Heating