First results from a study into the abundance trends of oxygen in the
Galactic thin and thick disks are presented. Oxygen abundances for 21 thick
disk and 42 thin disk F and G dwarf stars based on very high resolution spectra
(R\sim 215000) and high signal-to-noise (S/N>400) of the faint forbidden oxygen
line at 6300 A have been determined. We find that [O/Fe] for the thick disk
stars show a turn-down, i.e. the ``knee'', at [Fe/H] between -0.4 and -0.3 dex
indicating the onset of SNe type Ia. The thin disk stars on the other hand show
a shallow decrease going from [Fe/H] \sim -0.7 to the highest metallicities
with no apparent ``knee'' present indicating a slower star formation history.Comment: To be published in "CNO in the Universe", ASP Conference Series, C.
Charbonnel, D. Schaerer & G. Meynet (eds.
