A solar spectroscopic absolute abundance of argon from RESIK

TL;DR

This study measures the absolute abundance of argon in solar flare plasmas using RESIK X-ray spectrometer data, finding values consistent with photospheric levels and theoretical predictions.

Contribution

First spectroscopic determination of solar argon abundance from RESIK data, confirming its similarity to photospheric abundance and validating temperature-dependent line flux models.

Findings

Argon abundance in flare plasmas is about 6.45.

Measured Ar abundance aligns with recent solar abundance compilations.

Results support similar photospheric and coronal argon levels.

Abstract

Observations of He-like and H-like Ar (Ar XVII and Ar XVIII) lines at 3.949 Angstroms and 3.733 Angstroms respectively with the RESIK X-ray spectrometer on the CORONAS-F spacecraft, together with temperatures and emission measures from the two channels of GOES, have been analyzed to obtain the abundance of Ar in flare plasmas in the solar corona. The line fluxes per unit emission measure show a temperature dependence like that predicted from theory, and lead to spectroscopically determined values for the absolute Ar abundance, A(Ar) = 6.44 pm 0.07 (Ar XVII) and 6.49 pm 0.16 (Ar XVIII) which are in agreement to within uncertainties. The weighted mean is 6.45 pm 0.06, which is between two recent compilations of the solar Ar abundance and suggest that the photospheric and coronal abundances of Ar are very similar.