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OATS-UNI/TS SEMINAR
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Speaker: Cristina Chiappini (Geneva University)

Title: Spinstars: the first polluters of the Universe?
Date: Friday, May 20th, 2011
Time: 11:00
Venue: Villa Bazzoni

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Abstract: The chemical enrichment of the Universe in elements heavier than helium (metals) started as early as 300 Myrs after the Big Bang, upon the death of the first massive stars. Although already dead, their chemical imprints can be observed today in very-metal-poor halo stars (with one-thousandth or less of the solar iron). I will show that we have reasons to believe that a large fraction of the massive stars in the early Universe were fast rotators (spinstars). So far the chemical signatures of spinstars had been found only in the MW halo. Recently we found the imprints of fast rotators also in the Bulge, for the first time, in its oldest globular cluster. In addition, we show that spinstars could have been important contributors to the s-process elements in the early Universe, with important consequences on our understanding of the cosmic chemical enrichment. Fast stellar rotation could have been a common property of stars in the Early Universe, and is now also supported by the latest hydrodynamic simulations of the formation of the first stars. The impact of an early generation of fast rotating stars is manifold and goes beyond chemistry, probably also playing a role in the re-ionization of the Universe.
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Contact: Valentina D'Odorico (INAF - OAT)