Volume 384, Number 2, MarchIII 2002
|Page(s)||545 - 553|
|Section||Interstellar and circumstellar matter|
|Published online||15 March 2002|
Abundance stratification and pulsation in the atmosphere of the roAp star Equulei*
Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, 109017 Moscow, Russia e-mail: email@example.com
2 Institute for Astronomy, University of Vienna, Türkenschanzstrasse 17, 1180 Wien, Austria e-mail: firstname.lastname@example.org
3 Uppsala Astronomical Observatory, Box 515, 751 20, Sweden e-mail: email@example.com, firstname.lastname@example.org
4 Tavrian National University, Yaltinskaya 4, 330000 Simferopol, Crimea, Ukraine e-mail: email@example.com
Corresponding author: W. W. Weiss, firstname.lastname@example.org
Accepted: 10 January 2002
We present the evidence for abundance stratification in the atmosphere of the rapidly oscillating Ap star γ Equ. Ca, Cr, Fe, Ba, Si, Na seem to be overabundant in deeper atmospheric layers, but normal to underabundant in the upper layers with a transition in the typical line forming region of . This stratification profile agrees well with diffusion theory for Ca and Cr, developed for cool magnetic stars with a weak mass loss of yr-1. Pr and Nd from the rare earth elements have an opposite profile. Their abundance is more than 6 dex higher above than in the deeper atmospheric layers. We further discuss the implications of abundance stratification in the context of radial velocity amplitudes and phases observed by Kochukhov & Ryabchikova (2001) for a variety of spectral lines and elements using high spectral and time resolved, high S/N observations.
Key words: stars: chemically peculiar / stars: abundances / stars: oscillations / stars: individual: γ Equ
© ESO, 2002
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