A. Recio-Blanco, P. de Laverny, C. Worley, N. C. Santos, C. Melo, G. Israelian
In spite of many observational efforts aiming to characterize the chemical
evolution of our Galaxy, not much is known about the origin of fluorine (F).
Models suggest that the F found in the Galaxy might have been produced mainly
in three different ways, namely, Type II supernovae, asymptotic giant branch
nucleosynthesis, or in the core of Wolf-Rayet stars. Only a few observational
measurements of F abundances are available in the literature and mostly for
objects whose characteristics might hamper an accurate determination of
fluorine abundance (e.g.,complex mixing and nucleosynthesis processes,
external/internal contamination). We derive the F abundances for a set of nine
cool main-sequence dwarfs in the solar neighbourhood, based on an unblended
line of the HF molecule at 2.3 microns. In addition, we study the s-process
elements of five of these stars. We acquire data using the high-resolution
IR-spectrograph CRIRES and gather FEROS data from the European Southern
Observatory archive. Several of the analysed stars seem to be slightly fluorine
enhanced with respect to the Sun, although no correlation is found between the
F abundance and the iron content. In addition, the most fluorine enriched stars
are also yttrium and zirconium enriched, which suggests that AGB fluorine
nucleosynthesis is the dominant source of fluorine production for the observed
stars. Nevertheless, the correlation between [F/Fe] and the s-elements is
rather weak and possibly masked by the uncertainties in the F abundance
measurements. Finally, we compare our derived F abundances to previous
measurements of alpha-element and iron-peak element abundances. Type II core
collapse Supernovae do not appear to be the main site of F production for our
targets, as no correlation seems to exist between the [F/Fe] and the [alpha/Fe]
ratios.
View original:
http://arxiv.org/abs/1201.3193
No comments:
Post a Comment