2005A&A...442..563M

Abundances of 11 chemical elements have been determined for 10 F and 12 A dwarfs (``normal'' and chemically peculiar) bona-fide and probable members of the Ursa Major Group (age about 500Myr). The abundances were determined in a uniform manner using a model atmosphere analysis by minimising the chi-square of grids of synthetic spectra to observed high resolution high S/N (R≃25000 and R≃70000 ) spectra obtained in three narrow spectral regions centered around 5075Å, 5525Å and 6160Å. Specifically, Takeda's (1995PASJ...47..287T ) semi-automated procedure was used to derive the abundances of C, O, Na, Mg, Si, Ca, Sc, Fe, Ni, Y, and Ba, the projected rotational velocity v_esini and the microturbulent velocity for each star analysed. In graphs [X/H] versus T_eff, the A stars exhibit larger star-to-star variations in [Fe/H], [Ni/H], and [Si/H] than the F dwarfs do. The abundance of nickel is the only one that appears to be correlated with that of iron.