Element abundances from solar flare spectra

Ratios of solar element abundances are determined for Ar/Ca, K/Ca, and Ca/Fe, from high-resolution solar flare X-ray spectra obtained from Naval Research Laboratory Bragg spectrometers flown on the US Department of Defense P78-1 spacecraft. Values of the ratios are: Ar/Ca = 0.65, K/Ca = 0.10, and Ca/Fe = 0.10. If the abundance of iron is taken to be coronal, i.e. log A(Fe) = 7.65 {log A(H) = 12}, then the abundances are: log A(Ca) = 6.62, log A(Ar) = 6.44, log A(K) = 5.62. If the iron abundance is assumed to be photospheric, i.e., log A(Fe) = 7.50, then the abundances are: log A(Ca) = 6.47, log A(Ar) = 6.29, log A(K) = 5.47. The uncertainties in abundance ratios are ± 25 percent. The abundance results are discussed in terms of the possibility of varying abundances in the solar atmosphere.