Highly Ionized Potassium Lines in Solar X-ray Spectra and the Abundance of Potassium

The abundance of potassium is derived from X-ray lines observed during flares by the RESIK instrument on the solar mission CORONAS-F between 3.53 A and 3.57 A. The lines include those emitted by He-like K and Li-like K dielectronic satellites, which have been synthesized using the CHIANTI atomic cod...

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Bibliographic Details
Published in:The Astrophysical journal 2010-02, Vol.710 (1), p.804-809
Main Authors: Sylwester, J, Sylwester, B, Phillips, K. J. H, Kuznetsov, V. D
Format: Article
Language:English
Subjects:
ABUNDANCE
ALKALI METALS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ATMOSPHERES
CHROMOSPHERE
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION
GAMMA RADIATION
IONIZATION POTENTIAL
IONIZING RADIATIONS
MAIN SEQUENCE STARS
METALS
POTASSIUM
RADIATIONS
SATELLITES
SOLAR ATMOSPHERE
SPECTRA
STARS
STELLAR ATMOSPHERES
SUN
X RADIATION
X-RAY SPECTRA
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Summary:The abundance of potassium is derived from X-ray lines observed during flares by the RESIK instrument on the solar mission CORONAS-F between 3.53 A and 3.57 A. The lines include those emitted by He-like K and Li-like K dielectronic satellites, which have been synthesized using the CHIANTI atomic code and newly calculated atomic data. There is good agreement between observed and synthesized spectra, and the theoretical behavior of the spectra with varying temperature estimated from the ratio of the two GOES channels is correctly predicted. The observed fluxes of the He-like K resonance line per unit emission measure give log A(K) = 5.86 (on a scale log A(H) = 12), with a total range of a factor 2.9. This is higher than photospheric abundance estimates by a factor 5.5, a slightly greater enhancement than for other elements with first ionization potential (FIP) less than {approx}10 eV. There is, then, the possibility that enrichment of low-FIP elements in coronal plasmas depends weakly on the value of the FIP which for K is extremely low (4.34 eV). Our work also suggests that fractionation of elements to form the FIP effect occurs in the low chromosphere rather than higher up, as in some models.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/710/1/804