STELLAR ATMOSPHERIC PARAMETERS FOR F-G-K STARS FROM LOW-RESOLUTION DATA - METHOD AND APPLICATION TO A SAMPLE OF PROPER MOTION STARS

We develop a general method which allows us to derive fundamental stel lar parameters (T(eff), [M/H]) of F, G, and K dwarfs from low-resoluti on spectra covering the wavelength range 370-780 nm and using three di fferent grids of model atmosphere flux distributions. Two extreme case s are explored: (1) broad-band synthetic color indices, which exploit a large fraction of the available wavelength range, but at highly degr aded spectral resolution, and (2) synthetic spectrum fitting, which ta kes full advantage of the available resolution in the data, but which is limited to a relatively narrow wavelength interval. We show that, w hile in either case the initial model-derived parameter values differ systematically from published results obtained via high-resolution spe ctroscopy these spectroscopic data can be used to properly calibrate t he models. Thus, as an application, we were able to derive abundances for 40 proper motion stars, selected from Fresneau (1990). Within the systematic biases that could exist, the derived metallicity distributi on is bimodal, one mode centered on [M/H] = 0.0dex (thin disk) and the other on [M/H] = -0.6dex (thick disk), biased towards the thick disk. Furthermore, three low metallicity stars and a super metal-rich one h ave been discovered.