Meynet and Arnould (1993) have suggested that Wolf-Rayet (WR) stars could
significantly contaminate the Galaxy with 19F. In their scenario, 19F is
synthesized at the beginning of the He-burning phase from the 14N left over by
the previous CNO-burning core, and is ejected in the interstellar medium when
the star enters its WC phase. Recourse to CNO seeds makes the 19F yields
metallicity-dependent. These yields are calculated on grounds of detailed
stellar evolutionary sequences for an extended range of initial masses (from 25
to 120 Msol) and metallicities (Z = 0.008, 0.02 and 0.04). The adopted mass
loss rate prescription enables to account for the observed variations of WR
populations in different environments. The 19F abundance in the WR winds of 60
Msol model stars is found to be about 10 to 70 times higher than its initial
value, depending on the metallicity. This prediction is used in conjunction
with a very simple model for the chemical evolution of the Galaxy to predict
that WR stars could be significant (dominant?) contributors to the solar system
fluorine content. We also briefly discuss the implications of our model on the
possible detection of fluorine at high redshift.Comment: 2 figures; requires LaTeX A&A class file; accepted for publication in
Astron. Astrophy
