A semi-automatic procedure for abundance determination of A- and F-type stars

A variety of physical processes leading to different types of pulsations and chemical compositions is observed among A- and F-type stars. To investigate the underlying mechanisms responsible for these processes in stars with similar locations in the H-R diagram, an accurate abundance determination is needed, among others. Here, we describe a semi-automatic procedure developed to determine chemical abundances of various elements ranging from helium to mercury for this type of stars. We test our procedure on synthetic spectra, demonstrating that our procedure provides abundances consistent with the input values, even when the stellar parameters are offset by reasonable observational errors. For a fast-rotating star such as Vega, our analysis is consistent with those carried out with other plane-parallel model atmospheres. Simulations show that the offsets from the input abundances increase for stars with low inclination angle of about 4 degrees. For this inclination angle, we also show that the distribution of the iron abundance found in different regions is bimodal. Furthermore, the effect of rapid rotation can be seen in the peculiar behaviour of the H_beta line.