Improved data for solar flare X-ray spectral analysis

Abstract

Abstract. The inclusion of collisional rates for He-like Fe and Ca ions is discussed with reference to the analysis of solar flare Fe  and Ca  line emission, particularly from the Yohkoh Bragg Crystal Spectrometer (BCS). The new data are a slight improvement on calculations presently used in the BCS analysis software in that the discrepancy in the Fe  y and z line intensities (observed larger than predicted) is reduced. Values of electron temperature from satellite-to-resonance line ratios are slightly reduced (by up to 1 MK) for a given observed ratio. The new atomic data will be incorporated in the Yohkoh BCS databases. The data should also be of interest for the analysis of high-resolution, non-solar spectra expected from the Constellation-X and Astro-E space missions. A comparison is made of a tokamak S  spectrum with a synthetic spectrum using atomic data in the existing software and the agreement is found to be good, so validating these data for particularly high-n satellite wavelengths close to the S  resonance line. An error in a data file used for analyzing BCS Fe  spectra is corrected, so permitting analysis of these spectra.

X-ray emission from solar flares

“…In order to study the Fe and Fe/Ni line emission it is rather more important to study their evolution with the flare development, i.e., as a function of temperature because the line emission and its intensity vary with temperature and emission measure (Phillips 2004). It may be noted from Fig.…”

“…The Fe-line complex is due mostly to the 1s-2p transitions in He-like and H-like iron, FeXXV and FeXXVI respectively, with associated satellite lines. The weaker Fe/Ni line feature at ∼ 8 keV made up of emission from He-like nickel and more highly excited FeXXV ions is also evident in the more intense flares (Phillips 2004;Phillips et al 2004).…”

“…The measurements of soft X-ray flux before and during the flare provide a wonderful opportunity to study the soft X-ray characteristics of active region corona. The high sensitivity of the SLD and sub-keV energy resolution of Si PIN detector allows measuring of the intensity and mean energy of the Fe and Fe/Ni line features at approximately 6.7 and 8 keV respectively (Phillips 2004;Jain et al 2005Jain et al , 2006bPhillips et al 2006) as a function of time in all classes of flares. The Fe-line complex is due mostly to the 1s-2p transitions in He-like and H-like iron, FeXXV and FeXXVI respectively, with associated satellite lines.…”

“…The equivalent width of the Fe-line feature was observed to exceed the theoretical one in the temperature range of ≈ 20-60 MK, which could indicate multi-thermal flare plasma or higher iron abundance. The ratio of the 6.7 keV Fe to the 8.0 keV Fe/Ni line fluxes is therefore expected to decrease progressively with higher plasma temperature (Phillips 2004).…”

Solar X-ray Spectrometer (Soxs) Mission on Board GSAT2 Indian Spacecraft: The Low-Energy Payload

“…This line complex is due mostly to the 1s-2p transitions in He-like and H-like iron, FeXXV and FeXXVI respectively, with associated satellite lines. Another weaker line complex at ∼8 keV made up of emission from He-like nickel and more highly excited FeXXV ions is also evident in the more intense flares (Phillips, 2004;Phillips et al, 2004). Detailed calculations of emission line intensities as a function of temperature, with provision for different element abundance sets (e.g., photospheric or coronal), are given by the MEKAL/SPEX atomic codes (Mewe, Gronenschild, and van den Oord, 1985; and the CHIANTI code (Dere et al, 1997).…”