Highly ionized Calcium and Argon X-ray spectra from a large solar flare

Abstract

X-ray lines of helium-like calcium (\ion{Ca}{19}) between 3.17~Å and 3.21~Å and associated \ion{Ca}{18} dielectronic satellites have previously been observed in solar flare spectra, and their excitation mechanisms are well established. Dielectronic satellites of lower ionization stages (\ion{Ca}{17}~--~\ion{Ca}{15}) are not as well characterized. Several spectra during a large solar flare in 2001 by the DIOGENESS X-ray spectrometer on the {\em CORONAS-F}\/ spacecraft show the \ion{Ca}{17} and \ion{Ca}{16} satellites as well as lines of ionized argon (\ion{Ar}{17}, \ion{Ar}{16}) including dielectronic satellites. The DIOGENESS spectra are compared with spectra from a synthesis code developed here based on an isothermal assumption with various atomic sources including dielectronic satellite data from the Cowan Hartree--Fock code. Best-fit comparisons are made by varying the temperature as the code's input (Ar/Ca abundance ratio fixed at 0.33); close agreement is achieved although with adjustments to some ion fractions. The derived temperature is close to that derived from the two {\em GOES}\/ X-ray channels, $T_{\mathrm{GOES}}$. Some lines are identified for the first time. Similar spectra from the {\em P78-1}\/ spacecraft and the Alcator C-Mod tokamak have also been analyzed and similar agreement obtained. The importance of blends of calcium and argon lines is emphasized, affecting line ratios used for temperature diagnostics. This analysis will be applied to the {\em Solar Maximum Mission}\/ Bent Crystal Spectrometer archive and to X-ray spectra expected from the ChemiX instrument on the Sun-orbiting {\em Interhelioprobe}\/ spacecraft, while the relevance to X-ray spectra from non-solar sources is indicated.

arXiv commentTo be published, Astrophysical Journal

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Cited by in corpus (6)

• A Neutral Beam Model for High-Energy Neutrino Emission from the Blazar TXS 0506+056
• New Solar Flare Calcium Abundances with no Surprises: Results from the SMM Bent Crystal Spectrometer
• The soft X-ray spectrometer polarimeter SolpeX
• Varying Calcium Abundances in Solar Flares seen by Solar Maximum Mission
• The Observation of High-Energy Neutrinos from the Cosmos: Lessons Learned for Multimessenger Astronomy
• A Unique Resource for Solar Flare Diagnostic Studies: the SMM Bent Crystal Spectrometer