Issue A&A Volume 415, Number 3, March I 2004 Page(s) 1099 - 1112 Section Stellar atmospheres DOI http://dx.doi.org/10.1051/0004-6361:20031470

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. Ness

Hamburger 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

What is OpenURL?