Silicon abundance from RESIK solar flare observations

Abstract

The RESIK instrument on the CORONAS-F spacecraft obtained solar flare and active region X-ray spectra in four channels covering the wavelength range 3.8 -- 6.1 Åin its operational period between 2001 and 2003. Several highly ionized silicon lines were observed within the range of the long-wavelength channel (5.00 -- 6.05 Å). The fluxes of the \sixiv Ly-$\beta$ line (5.217 Å) and the \sixiii $1s^2-1s3p$ line (5.688 Å) during 21 flares with optimized pulse-height analyzer settings on RESIK have been analyzed to obtain the silicon abundance relative to hydrogen in flare plasmas. As in previous work, the emitting plasma for each spectrum is assumed to be characterized by a single temperature and emission measure given by the ratio of emission in the two channels of GOES. The silicon abundance is determined to be $A(\mathrm{Si})=7.93\pm .21$ (\sixiv) and $7.89\pm .13$ (\sixiii) on a logarithmic scale with H = 12. These values, which vary by only very small amounts from flare to flare and times within flares, are $2.6\pm 1.3$ and $2.4\pm 0.7$ times the photospheric abundance, and are about a factor of three higher than RESIK measurements during a period of very low activity. There is a suggestion that the Si/S abundance ratio increases from active regions to flares.

To be published, Solar Physics

References in corpus (2)

• The Solar Flare Iron Abundance
• The Solar Flare Sulphur Abundance from RESIK Observations

Cited by in corpus (6)

• The FIP and Inverse FIP Effects in Solar and Stellar Coronae
• Plasma composition in a sigmoidal anemone active region
• Solar Flare Composition and Thermodynamics from RESIK X-ray Spectra
• RESIK Solar X-ray flare element abundances on a non-isothermal assumption
• Highly ionized Calcium and Argon X-ray spectra from a large solar flare
• On the Application of Differential Evolution to the Analysis of X-Ray Spectra