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arXiv · 0806.1462

RESIK observations of He-like Ar X-ray line emission in solar flares

J. Sylwester·B. Sylwester·K. J. H. Phillips
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Abstract

The Ar XVII X-ray line group principally due to transitions 1s2 - 1s2l (l=s, p) near 4 Anstroms was observed in numerous flares by the RESIK bent crystal spectrometer aboard CORONAS-F between 2001 and 2003. The three line features include the Ar XVII w (resonance line), a blend of x and y (intercombination lines), and z (forbidden line), all of which are blended with Ar XVI dielectronic satellites. The ratio G, equal to [I(x+y) + I(z)]/I(w), varies with electron temperature Te mostly because of unresolved dielectronic satellites. With temperatures estimated from GOES X-ray emission, the observed G ratios agree fairly well with those calculated from CHIANTI and other data. With a two-component emission measure, better agreement is achieved. Some S XV and S XVI lines blend with the Ar lines, the effect of which occurs at temperatures greater than 8MK, allowing the S/Ar abundance ratio to be determined. This is found to agree with coronal values. A nonthermal contribution is indicated for some spectra in the repeating-pulse flare of 2003 February 6.

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J. Sylwester, B. Sylwester, K. J. H. Phillips. 2008-06-09. RESIK observations of He-like Ar X-ray line emission in solar flares. https://doi.org/10.1086/590533

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