Identifications of Fe XVII and Ni XIX in solar flares based on isoelectronic extrapolations

Abstract

Twenty-four lines in solar flare spectra in the region 200–410 Å have been identified as transitions between the 2s² 2p⁵ 3s, 3p and 3d configurations in Fe XVII and Ni XIX. The identifications are based on isoelectronic extrapolations of differences between experimental and theoretical wavenumbers along the neon-like sequence. A predicted wavelength for the magnetic dipole transition 2s² 2p⁵(³P₁–³P₀) in Fe XVII is also given.