CAMBRIDGE

1
CAMBRIDGE
UNIVERSITY OF
A benchmark study for CHIANTI based on RESIK
solar flare spectra
C. Chifor1 , G. Del Zanna2 , H. Mason1 , J. B.
Sylwester3 K.J.H. Phillips2
1DAMTP, University of Cambridge, UK 2MSSL
University College London, UK 3Space Research
Centre, Poland
5. Plasma diagnostics (a) Line Emission Measure
Loci Analysis
4. CHIANTI 5.2 vs. MEKAL
1. Introduction The CHIANTI package (Dere et al.
1997 Landi et al. 2006) contains up-to-date
atomic data including theoretical and observed
wavelengths as well as diagnostics tools for
astrophysical plasmas. As for any atomic code,
accuracy and completeness are paramount. We
perform a benchmark analysis for the recent
version 5.2 of CHIANTI, based on high-resolution
flare X-ray spectra obtained with RESIK, one of
the instruments on board the CORONAS-F mission.
RESIK is a high-resolution crystal spectrometer
operating in the wavelength range of 3.4 - 6.1 Å
which has been little explored by previous
observations. 2. RESIK solar flare observations

For a perfectly isothermal plasma, all EM curves
should intersect at a common point.
F observed flux at Earth Te electron
temperature Ne electron density G (Te, Ne)
line contribution function V emitting plasma
volume
(b) Continuum Emission Measure Loci Analysis

• Method analogous to the line EM analysis
• Total thermal continuum free-free
  free-bound 2-photon

(a)
(b)
Direct comparison in the RESIK wavelength range
between synthetic thermal continua (upper panels)
and emission lines (lower panels) from the
CHIANTI and MEKAL atomic codes. Default
parameters from MEKAL were input into CHIANTI we
used Meyer (1985) solar coronal abundances and
Arnaud Rothenflug (1985) ionisation fractions.
Assumed coronal abundances Mazzotta et al. (1998)
ionisation fractions
Assumed coronal abundances Mazzotta et al. (1998)
ionisation fractions
C5.8

• 6. Conclusions Future Work
• Both RESIK lines continuum are useful for
  determining the flaring plasma properties.
• RESIK spectral observations allow for an
  evaluation of the
• quality of data contained in CHIANTI.
• CHIANTI 5.2 and MEKAL predictions in the 3.4
  6.1 Å range are consistent, however we note that
  the atomic data for the
• Si XII and Si XIII ions is more complete in
  CHIANTI.
• The emitting plasma appears multi-thermal, an
  isothermal approximation not being found
  appropriate particularly
• during the impulsive phase of the flare.
• We are currently performing a differential
  emission measure (DEM) analysis using RESIK lines
  and continuum as well as RHESSI lines and
  continuum to constrain the distribution at high
  temperatures.
• A direct comparison between CHIANTI synthetic
  spectra and RESIK observations will be produced
  based on the derived DEM curve and assumed
  abundances.

3. RESIK cross - calibrations
RESIK average spectra of the 2003 February 22
flare
S XV w,x,y,z
Si XIII 3p
Si XIV Lyb
Si XIII 5p, 4p
S XVI Lya
Ar XVIII w,x,y,z
Si XIV 5p
S XV 3p
K XVIII
photons s-1 cm-2 Å-1
From comparisons with other solar instruments,
RESIK's precision in the continuum level is
confirmed to be within the 20 instrumental
uncertainties.