Jim Truran<br>

Department of Astronomy and Astrophysics, Enrico Fermi Institute, U. Chicago<br>

<i>Tracing the Abundance History of the Cosmos</i><p>

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The primordial compositions of galaxies reflect that of the Universe as it
emerged from the cosmological Big Bang: hydrogen, deuterium, 3He, 4He, and
7Li. Within galaxies, stars and supernovae play the dominant role in
synthesizing the elements from carbon through uranium and in returning
heavy-element-enriched matter to the interstellar gas from which new stars
are formed. This abundance history is written in the compositions of stars in
our Galaxy (and other galaxies). We review the nuclear processes that
participate in heavy element synthesis, identify the astrophysical sites
(stars and supernovae) with which they are associated, and note particularly
the (production) timescales on which this enrichment is expected to occur. We
then demonstrate how observations of often distinctive abundance patterns in
old (low metallicity) stellar populations can be used to trace and to
constrain the star formation and nucleosynthesis histories of galaxies and
the Universe.

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