AAS 199th meeting, Washington, DC, January 2002
Session 32. Russell Lecture
Invited, Monday, January 7, 2002, 11:40am-12:30pm, International Ballroom Center

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[32.01] The Distribution and Origin of Heavy Elements at High Redshifts

W. L. W. Sargent (Palomar Observatory, California Institute of Technology)

Stars in the Galactic halo have heavy element abundances as low as 1/10,000 of that in the sun. Below Fe/H ~ 1/300 of the solar value there is an increasing scatter in the relative abundances of various elements, including rare cases of very large overabundances of r-process elements perhaps synthesized in a single supernova. The overall distribution of r-process elements is thought to point to two early origins, one of them in primordial, supermassive stars. Metal-poor stars in nearby dwarf galaxies also give important information on early nucleosynthesis in metal-poor environments.

Studies of the absorption lines in the spectra of QSOs at very high redshifts, particularly the Damped Lyman-alpha absorbers, are yielding new information on the relative abundances of several elements and on the scatter in different lines of sight. I summarize this information and describe how it can be combined with the results derived from old stars to produce a picture of where and how the first heavy elements were synthesized.

This work was supported by the National Science Foundation under Grant AST-9900733.

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