Identification of Spectral Lines in the 500-1600 Å Wavelength Range of Highly Ionized Ne, Na, Mg, Ar, K, Ca, Ti, Cr, Mn, Fe, Co, and Ni Emitted by Flares (T_e>=3×10⁶ K) and Their Potential Use in Plasma Diagnostics

Abstract

On 1999 May 9 the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on the Solar and Heliospheric Observatory (SOHO) recorded spectra from a high-temperature region located in the solar corona above the west limb. These spectra contain lines from rather less-abundant elements in solar plasmas. In this paper we present identifications of the high-temperature (T_e>=3×10⁶ K) Ne, Na, Mg, Ar, K, Ca, Ti, Cr, Mn, Fe, Co, and Ni lines that were detected in the 500-1600 Å spectral range of SUMER. In addition, accurate wavelength measurements have been obtained with uncertainties varying between 0.015 and 0.040 Å (1 σ). Making use of the newly measured wavelengths, we derive energy levels in the ground configuration of a number of highly charged ions. We present intensity ratio calculations of lines in the SUMER range that could be used to measure electron densities in high-temperature solar plasmas. We also provide emissivities for Ca XIII-Ca XV and Fe XVIII-Fe XXIII lines that could be used to determine emission measures and electron temperatures of high-temperature plasmas. We discuss a method for measuring elemental abundance variations in high-temperature solar plasmas using lines presented in the paper. A list of spectral lines spanning the 300-30000 Å wavelength range and their branching ratios that are suitable for efficiency calibration of space-borne spectrographs is provided.