Lemaire, Joseph ; Katsiyannis, Athanassios

published in Solar Physics, 296 issue 4, pp. 64 (2021)

Abstract: This paper is a follow up of the article where Lemaire & Stegen (2016) introduced their DYN method to calculate coronal temperature profiles from given radial distributions of the coronal and solar wind (SW) electron densities. Several such temperature profiles are calculated and presented corresponding to a set of given empirical density models derived from eclipse observations and in-situ measurements of the electron density and bulk velocity at 1 AU. The DYN temperature profiles obtained for the equatorial and polar regions of the corona challenge the results deduced since 1958 from singular hydrodynamical models of the SW. In these models - where the expansion velocity transits through a singular saddle point - the maximum coronal temperature is predicted to be located at the base of the corona, while in all DYN models the altitude of the maximum temperature is found at significantly higher altitudes in the mid-corona. Furthermore, the maximum of the DYN-estimated temperatures is found at much higher altitudes over the polar regions and coronal holes, than over the equator. However, at low altitudes, in the inner corona, the DYN temperatures are always smaller at high latitudes, than at low equatorial latitudes. This appears well in agreement with existing coronal hole observations. These findings have serious implications on the open questions: what is the actual ource of the coronal heating, and where is the maximum energy deposited within the solar corona?

Keyword(s): Corona; Inner Corona, Models; Solar Wind; Solar Wind, Theory; Electron Density; Electron Temperature; Coronal Heating; Velocity Fields, Solar Wind
DOI: 10.1007/s11207-021-01814-4