Hydrogen Emission Spectra of Quiescent Prominences

Theoretical calculations of the combined radiative transfer and statistical equilibrium equation including the charge-particle conservations have been carried out for a multilevel hydrogen atom in quiescent prominences. Cool and dense models show the steep changes of population and radiation field in the vicinity of the surface, while these physical quantities remain unchanged for models with temperature of 7,300K, regardless of total densities. Ionization rate of hydrogen atom related with metallic line formation varies in considerable amounts from the surface to the center of model prominences cooler than 6,300K. However, such cool models cannot release enough hydrogen line emissions to explain observed intensities. Prominence models with a temperature higher than 8,000K can yield the centrally reversed Lyman line profiles confirmed by satellite EUV observations. We find that quiescent prominence with a density between 2x10^11 and 10^12 cm^-3 should be in temperature range between 6,300K and 8,300K, in order to explain consistently observed H alpha, beta line emissions and n_p/n_1 ratio.