Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-07-12
Astronomy and Astrophysics
Astrophysics
Accepted for publication in A&A, 21 pages, 7 figures
Scientific paper
10.1051/0004-6361:20065171
We present the results of a detailed NLTE abundance study of nine beta Cephei stars, all of them being prime targets for theoretical modelling: gamma Peg, delta Cet, nu Eri, beta CMa, xi1 CMa, V836 Cen, V2052 Oph, beta Cep and DD (12) Lac. The following chemical elements are considered: He, C, N, O, Mg, Al, Si, S and Fe. Our abundance analysis is based on a large number of time-resolved, high-resolution optical spectra covering in most cases the entire oscillation cycle of the stars. Nitrogen is found to be enhanced by up to 0.6 dex in four stars, three of which have severe constraints on their equatorial rotational velocity, \Omega R, from seismic or line-profile variation studies: beta Cep (\Omega R~26 km/s), V2052 Oph (\Omega R~56 km/s), delta Cet (\Omega R < 28 km/s) and xi1 CMa (\Omega R sin i < 10 km/s). The existence of core-processed material at the surface of such largely unevolved, slowly-rotating objects is not predicted by current evolutionary models including rotation. We draw attention to the fact that three stars in this subsample have a detected magnetic field and briefly discuss recent theoretical work pointing to the occurrence of diffusion effects in beta Cephei stars possibly capable of altering the nitrogen surface abundance. On the other hand, the abundances of all the other chemical elements considered are, within the errors, indistinguishable from the values found for OB dwarfs in the solar neighbourhood. Despite the mild nitrogen excess observed in some objects, we thus find no evidence for a significantly higher photospheric metal content in the studied beta Cephei stars compared to non-pulsating B-type stars of similar characteristics.
Aerts Christine
Briquet Maryline
Butler Keith
Morel Th.
Neiner Coralie
No associations
LandOfFree
Abundance analysis of prime B-type targets for asteroseismology I. Nitrogen excess in slowly-rotating beta Cephei stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Abundance analysis of prime B-type targets for asteroseismology I. Nitrogen excess in slowly-rotating beta Cephei stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Abundance analysis of prime B-type targets for asteroseismology I. Nitrogen excess in slowly-rotating beta Cephei stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-169116