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Resik observations of helium-like argon X-ray line emission in solar flares

Sylwester, J; Sylwester, B; Phillips, KJH; (2008) Resik observations of helium-like argon X-ray line emission in solar flares. ASTROPHYS J LETT , 681 (2) L117 - L120.

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Abstract

The Ar XVII X-ray line group principally due to transitions 1s(2)-1s2l (l = s, p) near 4 angstrom was observed in 2 numerous flares by the RESIK bent crystal spectrometer aboard CORONAS-F between 2001 and 2003. The three line features include 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) + I(y) + I(z)]/I(w), varies with electron temperature T-e 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 or similar to 8 MK, 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.

Type: Article
Title: Resik observations of helium-like argon X-ray line emission in solar flares
Keywords: line : identification, Sun : abundances, Sun : corona, Sun : flares, Sun : X-rays, gamma rays, SPECTRA, IONS
UCL classification: UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Space and Climate Physics
URI: http://discovery.ucl.ac.uk/id/eprint/143742
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