Distribution of temperature and emission measure in a steadily heated solar atmosphere

The distribution of temperature and emission measure in the stationary heated solar atmosphere was found for the limiting cases of slow and fast heating, when either the gas pressure or the concentration are constant through the layer depth. Results are relevant to the conditions when the energy injected by waves or by non-thermal particles or in some different way quickly transforms into a thermal flux. Under these conditions the temperature distribution with depth is determined by radiation loss and thermal conductivity, and at any values of energy flux and plasma concentration it is characterized by two universal functions. One of them gives the relation between the energy flux and temperature at the region boundary: the other - the temperature run with the depth. This run is such that a considerable part of the energy is radiated by a thin transition region with a very large temperature gradient.The results may be applied for calculation of the temperature and the emission measure both for the high temperature region of a flare, and for the quiet corona. The dimensionless structure of the transition region is the same for any value of the energy flux. These results concerning solar flares can help to explain the identity of optical spectra for flares of different types, the emission in a wide temperature interval from nearly the same region of space and the very small thickness of the region emitting optical lines. The latter is due to the shell structure of the flare as opposed to the usually assumed filamentary one.