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Element stratification in the atmospheres of two weakly magnetic Cr-type Ap stars

Published online by Cambridge University Press:  02 March 2005

T. Ryabchikova
Affiliation:
Institute of Astronomy, Russian Academy of Science, 48 Pyatnitskaya str., 119017 Moscow, Russia email: ryabchik@inasan.rssi.ru Institute for Astronomy, Vienna University, Türkenschanzstraße 17, A-1180 Vienna, Austria
F. Leone
Affiliation:
INAF - Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
O. Kochukhov
Affiliation:
Institute for Astronomy, Vienna University, Türkenschanzstraße 17, A-1180 Vienna, Austria
S. Bagnulo
Affiliation:
European Southern Observatory, Casilla 19001, Santiago 19, Chile
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Abstract

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We present results of stratification analyses for Mg, Si, Ca, Cr and Fe in the atmospheres of two Cr-type sharp-lined peculiar stars HD 133792 and HD 204411. Even in the absence of strong magnetic fields their atmospheres are stable which is confirmed by zero microturbulence. Both stars are slightly evolved, their $\log g \approx 3.5$, whereas their effective temperatures are 9200 and 8400 K, respectively. We find a moderate Cr and Fe stratification. However the abundances of these elements do not fall below the solar value throughout the atmosphere. Si and Ca are strongly stratified, in particular in HD 133792, with large underabundances in the outer atmospheric layers. Abundance stratifications derived for weakly magnetic Ap stars are compared with the empirically determined stratification in the atmospheres of strongly magnetic Ap stars in the same temperature range.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Type
Contributed Papers
Copyright
© 2004 International Astronomical Union