Details

Autor(en) / Beteiligte

• Gebran, M.
• Monier, R.

Titel

Chemical composition of A and F dwarfs members of the Pleiades open cluster

Ist Teil von

• Astronomy and astrophysics (Berlin), 2008-05, Vol.483 (2), p.567-570

Ort / Verlag

Les Ulis: EDP Sciences

Erscheinungsjahr

2008

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Aims. We derive the abundances of 18 chemical elements for 16 A-dwarf, both normal and chemically-peculiar, and 5 F-dwarf members of the Pleiades open cluster to place constraints on evolutionary models. Methods. Abundances and rotational and microturbulent velocities were derived by fitting synthetic spectra to high-resolution (R ~ 42 000 and R ~ 75 000) observations of high signal-to-noise ratio (S/N). Results. The abundances exhibit correlation with neither the effective temperature nor the projected rotational velocity. Interestingly, A stars exhibit larger star-to-star variations in C, Sc, Ti, V, Cr, Mn, Sr, Y, Zr and Ba, than F stars. F stars have solar abundances of almost all elements. In A stars, the abundances of Si, Ti and Cr are correlated with that of Fe, and the [X/Fe] ratios are solar for these three elements. The derived abundances are compared with the predictions of evolutionary models for the age of Pleiades (100 Myr). For F stars, small predicted underabundances of light elements and overabundances of Cr, Fe and Ni are confirmed by our findings. For A stars, the predicted overabundances in iron-peak elements are confirmed for a few stars only. Conclusions. The large scatter in the abundances of A stars, discovered previously in the Hyades, Coma Berenices, UMa group, and in field stars, appears to be a characteristic property of dwarf A stars. Hydrodynamical processes competing with radiative diffusion in the radiative zone of A dwarfs, could account for the scatter in abundances that we determine.