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Seminars at FGG

Chemical abundances in the polar disk of NGC4650A: implications for cold accretion scenario

Speaker: Marilena Spavone (Universita di Napoli Federico II)

Date and time: 2010-05-13 10:00

The aim of the present study is to test whether the cold accretion of gas through a "cosmic filament" (Maccio' et al. 2006) is a possible formation scenario for the polar disk galaxy NGC 4650A. If polar disks form from cold accretion of gas, the abundances of the HII regions may be similar to those of very late-type spiral galaxies. The deep spectra available allowed us to measure the Oxygen abundances (12 + log (O/H)) using the "Empirical method" based on intensities of the strongest emission lines, and the "Direct method", based on the determination of the electron temperature from the detection of weak auroral lines. The low metallicity value in the polar disk NGC 4650A and the flat metallicity gradient are both consistent with a later infall of metal-poor gas, as expected in the cold accretion processes.