HIGHLY IONIZED POTASSIUM LINES IN SOLAR X-RAY SPECTRA AND THE ABUNDANCE OF POTASSIUM

Journal Article · Wed Feb 10 00:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/710/1/804· OSTI ID:21394488

Sylwester, J; Sylwester, B ^[1]; Phillips, K J. H. ^[2]

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1. Space Research Centre, Polish Academy of Sciences, 51-622, Kopernika 11, Wroclaw (Poland)
2. Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT (United Kingdom)

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.

• OSTI ID: 21394488
• Journal Information: Astrophysical Journal, Vol. 710, Issue 1; Other Information: DOI: 10.1088/0004-637X/710/1/804; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABUNDANCE
CHROMOSPHERE
EMISSION
GAMMA RADIATION
IONIZATION POTENTIAL
POTASSIUM
SATELLITES
SUN
X RADIATION
X-RAY SPECTRA
ALKALI METALS
ATMOSPHERES
ELECTROMAGNETIC RADIATION
ELEMENTS
IONIZING RADIATIONS
MAIN SEQUENCE STARS
METALS
RADIATIONS
SOLAR ATMOSPHERE
SPECTRA
STARS
STELLAR ATMOSPHERES