A. Fludra et Jt. Schmelz, ABSOLUTE ABUNDANCES OF FLARING CORONAL PLASMA-DERIVED FROM SMM SPECTRAL OBSERVATIONS, The Astrophysical journal, 447(2), 1995, pp. 936-943
X-ray spectra simultaneously observed by the Flat Crystal Spectrometer
and Bent Crystal Spectrometer on Solar Maximum Mission have been anal
yzed for two solar flares. Elemental abundances for O, Ne, Mg, Si, S,
Ca, and Fe with respect to hydrogen have been derived with the aid of
a differential emission measure analysis. Absolute abundances of eleme
nts with a high first ionization potential (FIP) are depleted in the c
orona relative to their photospheric values. An indication for a gradu
al change in the coronal-to-photospheric abundance ratio as a function
of FIP is found, rather than the step-function distribution associate
d with solar energetic particles. The coronal abundance of low-FIP cal
cium is enhanced by a factor of 1.5-2.0, while the high-FIP oxygen is
depleted by a factor of 0.25, with respect to photospheric abundances.
Anomalous values of neon and argon abundances are discussed.