Oxygen abundances in the Galactic Bulge: evidence for fast chemical   enrichment
  AIMS: We spectroscopically characterize the Galactic Bulge to infer its star formation timescale, compared to the other Galactic components, through the chemical signature on its individual stars.   METHODS: We derived iron and oxygen abundances for 50 K giants in four fields towards the Galactic bulge. High resolution (R=45,000) spectra for the target stars were collected with FLAMES-UVES at the VLT.   RESULTS: Oxygen, as measured from the forbidden line at 6300 \AA, shows a well-defined trend with [Fe/H], with [O/Fe] higher in bulge stars than in thick disk ones, which were known to be more oxygen enhanced than thin disk stars.   CONCLUSIONS: These results support a scenario in which the bulge formed before and more rapidly than the disk, and therefore the MW bulge can be regarded as a prototypical old spheroid, with a formation history similar to that of early-type (elliptical) galaxies. 
M. Zoccali, A. Lecureur, B. Barbuy, V. Hill, A. Renzini, D. Minniti,   Y. Momany, A. Gomez, S. Ortolani