| Issue |
A&A
Volume 384, Number 2, MarchIII 2002
|
|
|---|---|---|
| Page(s) | 545 - 553 | |
| Section | Interstellar and circumstellar matter | |
| DOI | https://doi.org/10.1051/0004-6361:20020057 | |
| Published online | 15 March 2002 | |
Abundance stratification and pulsation in the atmosphere of the roAp star 
Equulei*
1
Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, 109017 Moscow, Russia e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
2
Institute for Astronomy, University of Vienna, Türkenschanzstrasse 17, 1180 Wien, Austria e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
3
Uppsala Astronomical Observatory, Box 515, 751 20, Sweden e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
, This email address is being protected from spambots. You need JavaScript enabled to view it.
4
Tavrian National University, Yaltinskaya 4, 330000 Simferopol, Crimea, Ukraine e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Corresponding author: W. W. Weiss, This email address is being protected from spambots. You need JavaScript enabled to view it.
Received:
11
October
2001
Accepted:
10
January
2002
Abstract
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
Based on observations obtained at the European Southern Observatory (La Silla, Chile), and the South African Astronomical Observatory.
© ESO, 2002
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