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Astron. Astrophys. 357, 981-987 (2000)


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Abundance analyses of roAp stars

VI. 10 Aql and HD 122970 *

T.A. Ryabchikova 1,2, I.S. Savanov 3,6, A.P. Hatzes 4, W.W. Weiss 1 and G. Handler 1,5

1 Institute for Astronomy, University of Vienna, Türkenschanzstrasse 17, 1180 Vienna, Austria (Ryabchikova,Weiss,Handler@galileo.astro.univie.ac.at)
2 Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, 109017 Moscow, Russia (ryabchik@inasan.rssi.ru)
3 Crimean Astrophysical Observatory, 334413 Nauchny, Crimea, Ukraine (savanov@crao.crimea.ua)
4 Department of Astronomy and McDonald Observatory, University of Texas at Austin, Austin, Texas 78712, USA (artie@zorba.as.utexas.edu)
5 South African Astronomical Observatory, P.O.Box 9, Observatory 7935, South Africa (gerald@saao.ac.za)
6 Isaac Newton Institute of Chile, Crimean Branch

Received 8 March 2000 / Accepted 13 April 2000

Abstract

In this sixth paper in a sequence on abundance analyses of roAp stars we present the results for two further members of this group, which are fairly similar and have only a small magnetic field. The analysis of 10 Aql and HD 122970 did not require, for the first time in this long term project, the development of tools and hence was rather straight-forward. We reanalyzed Sm, Eu and Gd in HD 203932, because better atomic parameters have become available with VALD-2; and for Eu we also took hyperfine-structure effects into account.

Similar to the five roAp stars analysed so far ([FORMULA] Cir: Kupka et al. 1996, HD 203932: Gelbmann et al. 1997, [FORMULA] Equ: Ryabchikova et al. 1997a, HD 24712: Ryabchikova et al. 1997b, and HD 166473: Gelbmann et al. 2000) we find nearly solar abundances of Fe and Ni, and a definite overabundance of Cr and especially Co, with large overabundances of rare earth elements. This pattern seems to be a common property of chemically peculiar (CP2, Ap) stars. HD 101065 (Przybylski's star), another roAp star, has a similar peculiarity pattern, except of iron (Cowley et al. 2000) which is underabundant.

10 Aql and HD 122970 provide another example for the anomalous line strengths of the second ions of rare earth elements resulting in an abundance increase of up to 2 dex (!) compared to values obtained from lines of the first ions. As we mentioned in an earlier paper, this anomaly yet is not found in non-roAp and "normal" stars.

Key words: stars: abundances – stars: chemically peculiar – stars: individual: 10 Aql, HD 122970 – stars: magnetic fields – stars: oscillations

* Based on observations obtained at Crimea and McDonald Observatories

Send offprint requests to: Werner W. Weiss

© European Southern Observatory (ESO) 2000

Online publication: June 5, 2000

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