The nonsolar abundance ratios of Arcturus deduced from spectrum synthesis

Using opacity distribution functions based on a newly expanded atomic and molecular line list, we have calculated a model atmosphere for Arcturus that reproduces the observed flux distribution. Individual line parameters in the list were adjusted to match the solar spectrum in a preliminary way, in the regions 5000-5500 A, 6000-6500 A, and 7500-9000 A. The Arcturus model spectrum calculated with these adjustments reproduces well the profiles of all lines in the observed spectrum of the Griffin atlas for which the solar gf-values are well determined. The Arcturus model has an iron abundance [Fe/H]=−0.5±0.1, a temperature T eff =4300±30 K, gravity log g=1.5±0.15, and an overabundance of the light metals