Temperature of the Solar Corona

Abstract

IT is quite possible that a temperature of the order of 2,300,000° K., mentioned in Dr. A. Hunter's article on this subject1, may be maintained in the solar corona by collisions of atoms, accelerated from distant regions by the gravitational field of the sun. It is difficult to estimate the resulting temperature without exact knowledge of coronal density, but if the radiation losses of the corona are neglected and equipartition of kinetic energy between ions and electrons is assumed, calculation gives a temperature of the order 20,000,000° K. for atoms of iron, accelerated from infinity to the surface of the sun. Radiation losses increase with the density and might be considerable in the inner corona, and equipartition of the energy might not be reached, so that the ionization maintained in the inner corona might be of the correct order, as required by Edlen's proposals ; but there is a possibility that in a more distant region there will be a layer of higher kinetic temperature and that the temperature decreases to that of the surface of the sun, as the sun is approached.