Title: The Solar Chromosphere: Is it always hot, or mainly cold? How is it heated?

Dr. Wolfgang Kalkofen
Harvard-Smithsonian Center for Astrophysics

The Sun belongs to a class of stars in which the energy generated in its interior is transported through the subsurface layers by convection. In the process, waves are emitted that heat the outer solar atmosphere. Are they mainly acoustic waves, internal gravity waves, or waves associated with magnetic fields? There is no agreement among students of this question. It comes as no surprise then that models of the structure of the solar chromosphere differ widely. In addition, the total radiative energy flux emitted from the chromosphere of the Sun appears to be atypical for its class. What is the problem? And conceivable solution? Numerical simulations of wave heating of the chromosphere as well as ground-based and space-based observations should answer the question. The usual criterion, agreement between observations of emergent radiation and model predictions, has failed to provide an answer. The question dates back to the middle of last century. Why has it not been answered? Or has it?

UT Arlington Physics