Abundance stratification and pulsation in the atmosphere of the roAp star γ Equulei
- Author(s)
- Tanya A. Ryabchikova, Nikolai E. Piskunov, Oleg Kochukhov, Vadim Tsymbal, Peter Mittermayer, Werner Wolfgang Weiss
- 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 -1.5 < log τ5000 < -0.5. This stratification profile agrees well with diffusion theory for Ca and Cr, developed for cool magnetic stars with a weak mass loss of ≈ 2.5 × 10-15 M⊙ yr-1. Pr and Nd from the rare earth elements have an opposite profile. Their abundance is more than 6dex higher above logτ5000 ≈ -8.0 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
- Organisation(s)
- Department of Astrophysics, Department of Inorganic Chemistry
- External organisation(s)
- Russian Academy of Sciences, Uppsala University
- Journal
- Astronomy & Astrophysics
- Volume
- 384
- Pages
- 545-553
- No. of pages
- 9
- ISSN
- 0004-6361
- Publication date
- 2002
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103003 Astronomy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/31d1b899-47bb-4f73-adca-1059146547f4