Claudio Vita-Finzi

The model outlined here embodies three distinct, successive mechanisms which both define and characterise the Sun’s chromosphere, transition region and corona. Operating experience from fusion research shows how Spitzer resistivity may render ohmic heating in the chromosphere self-limiting and thus serve to define the lower margin of the transition region; its upper margin is at ~6.103 K, where radiative cooling of He/H plasma decelerates sharply. The third and last stage in the proposed scheme is expansion into the tenuous plasma of space, which leads to the acceleration of ions to high energies, long recorded by spacecraft instruments as He++. There is thus dynamic continuity all the way from the solar interior - the energy source for spinning columns in the Rayleigh–Bénard setting of the convection zone - to the coronal exhalation of the solar wind, a finding which should benefit the analysis of space weather, witness the association between helium in the solar wind and the incidence of coronal mass ejections.