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Issue A&A
Volume 381, Number 3, January III 2002
Page(s) 959 - 970
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20011593



A&A 381, 959-970 (2002)
DOI: 10.1051/0004-6361:20011593

The abundance pattern of $\lambda$ Bootis stars

U. Heiter

Institute for Astronomy (IfA), University of Vienna, Türkenschanzstrasse 17, 1180 Vienna and Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-7215, USA
    e-mail: ulrike@fafnir.astr.cwru.edu

(Received 21 July 2001 / Accepted 25 October 2001 )

Abstract
Within a project to investigate the properties of $\lambda$ Bootis stars, we report on their abundance pattern. High resolution spectra have been obtained for a total of twelve candidate $\lambda$ Bootis stars, four of them being contained in spectroscopic binary systems, and detailed abundance analyses have been performed. All program stars show a characteristic $\lambda$ Bootis abundance pattern (deficient heavy elements and solar abundant light elements) and an enhanced abundance of Na. This work raises the fraction of $\lambda$ Bootis stars with known abundances to 50%. The resulting abundances complemented by literature data are used to construct a "mean $\lambda$ Bootis abundance pattern", which exhibits, apart from general underabundances of heavy elements ( $\approx$ -1 dex) and solar abundances of C, N, O, Na and S, a star-to-star scatter which is up to twice as large as for a comparable sample of normal stars.


Key words: stars: abundances -- stars: atmospheres -- binaries: spectroscopic -- stars: chemically peculiar -- stars: early-type

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© ESO 2002


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