THE SOLAR FLARE CHLORINE ABUNDANCE FROM RESIK X-RAY SPECTRA

The abundance of chlorine is determined from X-ray spectra obtained with the RESIK instrument on CORONAS-F during solar flares between 2002 and 2003. Using weak lines of He-like Cl, Cl XVI, between 4.44 and 4.50 A, and with temperatures and emission measures from GOES on an isothermal assumption, we...

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Bibliographic Details
Published in:The Astrophysical journal 2011-09, Vol.738 (1), p.49-jQuery1323904312770='48'
Main Authors: Sylwester, B., Phillips, K. J. H., Sylwester, J., Kuznetsov, V. D.
Format: Article
Language:English
Subjects:
ABUNDANCE
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CHLORINE
ELEMENT ABUNDANCE
ELEMENTS
HALOGENS
INFRARED SPECTRA
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
NONMETALS
SOLAR ACTIVITY
SOLAR FLARES
SPECTRA
STARSPOTS
STELLAR ACTIVITY
STELLAR FLARES
SUNSPOTS
X-RAY SPECTRA
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Summary:The abundance of chlorine is determined from X-ray spectra obtained with the RESIK instrument on CORONAS-F during solar flares between 2002 and 2003. Using weak lines of He-like Cl, Cl XVI, between 4.44 and 4.50 A, and with temperatures and emission measures from GOES on an isothermal assumption, we obtained A(Cl) = 5.75 ? 0.26 on a scale A(H) = 12. The uncertainty reflects an approximately a factor of two scatter in measured line fluxes. Nevertheless, our value represents what is probably the best solar determination yet obtained. It is higher by factors of 1.8 and 2.7 than Cl abundance estimates from an infrared sunspot spectrum and nearby H II regions. The constancy of the RESIK abundance values over a large range of flares (GOES class from below C1 to X1) argues for any fractionation that may be present in the low solar atmosphere to be independent of the degree of solar activity.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/738/1/49