Theoretical solar photon flux density at the earth emitted from the chromosphere (Np=1011cm-3, T=105oK , ΔR=104 km) for wavelengths near the Lyman ionization edge as observed with a resolution of 1.8 A (Gaussian halfwidth). (long dashes: recombination continuum; short dashes: discrete Lyman series without the radiative enhancement effect due to line broadening by plasma field fluctuations; solid curve: total flux including radiative enhancement of the Lyman series).
A reduction factor of 10-6 was necessary to yield an agreement with both the absolute flux and spectral shape at the solar Lyman ionization edge. This can probably be explained by scattering and photoionization effects which were not taken into account for the present emission model (in addition, the strong intensity drop for wavelengths greater than 912 A (which is observed experimentally) is the consequence of an assumed dependence of the detector efficiency on the coherency of the registered photons; otherwise the spectrum would not drop below the continuum level).
