Temperature-Density Structure in Coronal Helmets: the Quiescent Prominence and Coronal Cavity

Abstract

Physical processes which are most important in determining temperature and density distributions in closed coronal loop systems are studied within the context of how this type of magnetic geometry influences the local balance of mechanical energy flux, conductive flux, and radiative losses. For regions above the temperature maximum, there can be no net conductive loss since closed field lines prevent outward beat conduction and the vanishing temperature gradient at the level of the temperature maximum prohibits downward heat conduction there. Hence, the mechanical energy input at the base must ultimately be radiated away. This requirement, in addition to a condition on the lateral distribution of gas pressure at the level of T , is used in a computation which yields the density and temperature distribution throughout the helmet as a function of the mechanical energy input and magnetic field geometry. It is demonstrated that the quiescent prominences normally observed at the base of coronal helmets as well as the low-density cavity surrounding these structures are the natural consequences of the adjustment of density and temperature structui e in the helmet required to satisfy energy and mass balance conditions as modulated by the magnetic field.