| Abstract | PDF (320 KB) | PS (266 KB) | References | HTML | Simbad Objects | NASA ADS Abstract Service |
Free access article
A&A 415, 1099-1112 (2004)
DOI: 10.1051/0004-6361:20031470
Coronal abundances from high-resolution X-ray data: The case of Algol
J. H. M. M. Schmitt and J.-U. NessHamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
(Received 7 October 2002 / Accepted 9 September 2003 )
Abstract
We discuss the determination of elemental abundances from
high resolution X-ray data. We emphasize the need for an accurate
determination of the underlying temperature structure and advocate
the use of a line ratio method which allows us to utilize, first, the
strongest lines observed in the X-ray spectra, and second, lines that
span a rather wide temperature range. We point out the need
to use continuous emission measure distributions and show via example
that modeling in terms of individual temperature components yields
errors of more than 50%. We stress the need to derive differential
emission measure distributions based on physical assumptions and
considerations. We apply our methods to the Chandra LETGS
spectrum of Algol and show that nitrogen is considerably enhanced
compared to cosmic abundances by a factor of 2 while carbon is depleted
by at least a factor of 25. Iron, silicon, and magnesium,
are all depleted compared to cosmic
abundances, while the noble gas neon has the relatively highest
abundance.
Key words: stars: abundances -- stars: activity -- stars: coronae -- stars: late type -- X-rays: stars -- stars: individual: Algol
Offprint request: J. H. M. M. Schmitt, jschmitt@hs.uni-hamburg.de
SIMBAD Objects
© ESO 2004



Document 