G. Bono Abstract

The Transition between the Inner Disk and the Galactic Bulge

G. Bono (INAF/Osservatorio Astronomico di Roma)

We present new results concerning the metallicity gradient of the inner disk(R_G <= 7 kpc) using homogeneous and accurate iron measurements of classical Cepheids.  We found evidence of a steady increase in iron abundance when approaching the innermost regions of the thin disk. The metallicity is super—solar and approaches 0.4 dex for R_G~5.5 kpc. We also found that the Cepheids close to the edge of the inner disk are systematically more metal-rich than young stars located either along the Galactic Bar or in the Nuclear Bulge ([Fe/H]~0). Thus suggesting that the above regions have had different chemical enrichment histories. We will also briefly discuss recent findings concerning the age and the metallicity of the metal-rich bulge globular cluster NGC~6528 and briefly review the metallicity gradient of the Galactic bulge.