Carbon Abundances in F and G Dwarfs

We have determined carbon abundances or upper limits from the forbidden [C I] line at 8727.13 A for 85 F and early G type main sequence stars, with metallicities ranging between [Fe/H] = -1.0 and [Fe/H] = +0.25. The [C I] line has not been previously used for a study of this size. We find that the C/Fe abundance ratio is slowly decreasing with time and increasing metallicity in the disk, but with considerable observational scatter. A discussion of results in the literature supports this result. Our data do not reveal any gradients with galactocentric birth distance for our stars, but more accurate observations are desirable since possible gradients should be important to the question of the synthesis of C and Fe in the disk. (Accepted for publication in A&A. Postscript text and figures available via anonymous ftp to "chiron.astro.uu.se", in directory "pub/articles/atmos/P89")