Metallicism among A and F giant stars.

132 stars considered as A and F giants have been studied for their properties in the Geneva photometric system. It is shown that this system to derive the temperature, absolute magnitude and Fe/H value for stars in this part of the HR diagram. 36 percent of the stars of our sample exhibit an enhanced value Delta m2 that can be interpreted in terms of Fe/H. The red limit of stars having an enhanced Fe/H value is 0.225 in B2-V1 or 6500 K in Teff. This corresponds to the limit defined by Vauclair and Vauclair (1982) where the diffusion timescale is equal to the stellar lifetime and permits the assumption that the diffusion is the process responsible for the metallicism observed in the A and F giants.