Scaling laws of quiet-Sun coronal loops

Abstract

We study a series of relations between physical parameters in coronal loops of the quiet Sun reconstructed by combining tomographic techniques and modeling of the coronal magnetic field. We use differential emission measure tomography (DEMT) to determine the three-dimensional distribution of the electron density and temperature in the corona, and we model the magnetic field with a potential-field source-surface (PFSS) extrapolation of a synoptic magnetogram. By tracing the DEMT products along the extrapolated magnetic field lines, we obtain loop-averaged electron density and temperature. Also, loop-integrated energy-related quantities are computed for each closed magnetic field line. We apply the procedure to Carrington rotation 2082, during the activity minimum between Solar Cycles 23 and 24, using data from the Extreme Ultraviolet Imager on board the Solar Terrestrial Relations Observatory (STEREO) spacecraft. We find a scaling law between the loop-average density N and loop length L, N m ∼ L −0.35 , but we do not find a significant relation between loop-average temperature and loop length. We confirm though the previously found result that loop-average temperatures at the equatorial latitudes are lower than at higher latitudes. We associate this behavior with the presence at the equatorial latitudes of loops with decreasing temperatures along their length ("down" loops), which are in general colder than loops with increasing temperatures ("up" loops). We also discuss the role of "down" loops in the obtained scaling laws of heat-

Enthalpy-based modeling of tomographically reconstructed quiet-Sun coronal loops

“…We statistically study a large number of reconstructed loops for Carrington rotation (CR) 2082 obtaining a series of typical average loops of different lengths. We look for relations between the thermal properties and the lengths of the constructed typical loops and find similar results to those found in a previous work (Mac Cormack et al, 2020).…”

“…We statistically study a large number of reconstructed loops for Carrington rotation (CR) 2082 obtaining a series of typical average loops of different lengths. We look for relations between the thermal properties and the lengths of the constructed typical loops and find similar results to those found in a previous work (Mac Cormack et al, 2020).We also analyze the typical loop properties by comparing them with the zero-dimensional (0D) hydrodynamic model Enthalpy-Based Thermal Evolution of Loops (EBTEL, Klimchuk et al, 2008). We explore two heating scenarios.…”

“…In a previous work we studied CR 2082 searching for scaling laws between different properties of loops reconstructed with the tomography technique (Mac Cormack et al, 2020). As we mentioned in Section 1, in that work we found scaling laws between loop-average plasma properties and loop lengths obtained from the direct analysis of the full loop set.…”