Title: | SOLAR
FLARE ABUNDANCES OF POTASSIUM, ARGON, AND SULPHUR |
|
Authors: | K.J. H. PHILLIPS, J. SYLWESTER, B. SYLWESTER AND E. LANDI | |
Abstract: |
The absolute abundance of potassium has
been determined for the first time from X-ray solar flare line and
continuum spectra. The absolute and relative abundances of Ar and S
have also been determined. Assuming that the flare plasma is coronal,
and since potassium has the lowest first ionization potential (FTP) of
any common element on the Sun, this determination is of importance in
the continuing debate concerning the nature of the coronal/photospheric
element abundance ratios, which are widely considered to depend on the
FTP. The measurements were made with the RESIK crystal spectrometer
on the Coronas-F spacecraft. A differential emission measure
DEM
exp (-ßTe) was found to be the most consistent with the
data of three models considered. We find that the K/H abundance ratio
is (3.7 ± 1.0) x 10-7, a factor of 3 times photospheric.
Our measured values of the Ar/H ratio, (2.8 ± 0.2) x 10-6,
and of the S/H ratio, (2.2 ± 0.4) x 10-5, are equal to
previous coronal and photospheric determinations to within
uncertainties. These measurements therefore fit a pattern in which
low-FXP elements are enriched in the corona by a factor 3 and in which
high-FTP elements (including S) have equal coronal and photospheric
abundances.
Subject headings: Sun: abundances — Sun: corona — Sun: flares — Sun: X-rays, gamma rays
|
FULL VERSION-HTML | ||||
Figures: | Fig1. |
Fig2. |
||
Table: | Table1 |
Page created by Jaroslaw Bakala
( jb@cbk.pan.wroc.pl)
Web Curator: Janusz
Sylwester ( js@cbk.pan.wroc.pl)