Effect of a Magnetic Field on Coronal Heating.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Effect of a Magnetic Field on Coronal Heating. Uchida, Yutaka Abstract The shock wave heating theory (Schatzman, de Jager-Kuperus, and Osterbrock) of the solar corona is extended to include an effect of the magnetic field, and theoretical models of the solar coroi~a with and without the magnetic field have been investigated in a self-consistent scheme (to be published in Pub?. Astron. Soc. Japan 15, 376,1963). The solution is obtained numerically under given boundary conditions in the lowest chromosphere by including the heating and the support of the chromosphere in the time average in the same consistent scheme. This is made possible by the comparative smallness of the net radiative loss per mass in the quasi-thermodynamical equilibrium in the lower chromosphere. The presence of an outward- decreasing magnetic field makes the effective sound velocity greater in lower layers, and so makes the strength of the shock waves weaker around there. Accordingly the region of heat liberation is shifted up slightly out of the region of main radiation loss, which lies near the chromosphere-corona transitional region. A greater downward heat flow by conduction is required by this separation, and it in turn requires the presence of a steeper temperature rise to higher values in the model than is the case without the magnetic field. The density in the corona remains higher due to the longer scale height in this case, so that features like coronal condensalions in the plage regions around sunspots appear. Some additional results are given on the parame- ter dependence of the model including the depen deuce on gravity. This may lead to an investigation on the existence of coronas on other types of stars. Publication: The Astronomical Journal Pub Date: March 1964 DOI: 10.1086/109248 Bibcode: 1964AJ.....69..151U full text sources ADS |