Abundance Gradients as a tool for understanding the Formation of the Milky Way |
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Authors: | Cristina Chiappini |
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Institution: | (1) Osservatorio Astronomico di Trieste, Via Tiepolo 11, Trieste, TS, 34131, Italy |
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Abstract: | According to the two-infall model for the chemical evolution of the Galaxy the halo and bulge formed on a relatively short
timescale (0.8–1.0 Gyr) out of the first infall episode, whereas the disk accumulated much more slowly and ‘inside-out’ during
a second independent infall episode. We explored the effects of a threshold in the star formation process, during both the
halo and disk phases. In the comparison between model predictions and available data, we have focused our attention on abundance
gradients as well as gas, stellar and star formation rate distributions along the disk. We suggest that the mechanism for
the formation of the halo leaves detectable imprints on the chemical properties of the outer regions of the disk, whereas
the evolution of the halo and the inner disk are almost completely disentangled. This is due to the fact that the halo and
disk densities are comparable at large Galactocentric distances and therefore the gas lost from the halo can substantially
contribute to building up the outer disk. We predict that the abundance gradients along the Galactic disk have increased in
time during the first billion years of the disk evolution and remained almost constant in the last ~5Gyrs.
This revised version was published online in September 2006 with corrections to the Cover Date. |
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