ABSOLUTE ABUNDANCES OF FLARING CORONAL PLASMA-DERIVED FROM SMM SPECTRAL OBSERVATIONS

Citation
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
Citations number
42
Categorie Soggetti
Astronomy & Astrophysics
Journal title
ISSN journal
0004637X
Volume
447
Issue
2
Year of publication
1995
Part
1
Pages
936 - 943
Database
ISI
SICI code
0004-637X(1995)447:2<936:AAOFCP>2.0.ZU;2-N
Abstract
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.