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Abstract: Nearby galaxies are ideal places to study in detail metallicity gradients andtheir time evolution. We consider chemical abundances of a new sample of \hii\regions complemented with previous literature data-sets. We compare \hii\region and PN abundances obtained with a common set of observations taken atMMT. With an updated theoretical model, we follow the time evolution of thebaryonic components and chemical abundances in the disk of M33, assuming thatthe galaxy is accreting gas from an external reservoir. Supported by a uniformsample of nebular spectroscopic observations, we conclude that: {\em i} themetallicity distribution in M33 is very complex, showing a central depressionin metallicity probably due to observational bias; {\em ii} the metallicitygradient in the disk of M33 has a slope of -0.037$\pm$ 0.009 dex kpc$^{-1}$ inthe whole radial range up to $\sim$8 kpc, and -0.044$\pm$ 0.009 dex kpc$^{-1}$excluding the central kpc; {\em iii} there is a small evolution of the slopewith time from the epoch of PN progenitor formation to the present-time.}



Autor: Laura Magrini 1, Letizia Stanghellini 2, Edvige Corbelli 1, Daniele Galli 1, Eva Villaver 3 1 INAF, Osservatorio Astrofisico di A

Fuente: https://arxiv.org/







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