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Pinsonneault, Marc
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Institute: Ohio State
First Coauthor: G. Steigman
Second Coauthor: T. Walker
Presentation: Poster Display
Title: Stellar Mixing and the Primordial Lithium Abundance
Abstract: We compare the properties of recent samples of the lithium abundances in
halo stars to one another and to the predictions of theoretical models
including rotational mixing, and we examine the data for trends with metal
abundance. We find from a KS test that in the absence of any correction for
chemical evolution, the Ryan, Norris, & Beers (1999) sample is fully
consistent with mild rotational mixing induced depletion and, therefore,
with an initial lithium abundance higher than the observed value. Tests for
outliers depend sensitively on the threshold for defining their presence,
but we find a 10-45
rotationally mixed models with a 0.2 dex median depletion (with lower
probabilities corresponding to higher depletion factors). When chemical
evolution trends (Li/H versus Fe/H) are treated in the linear plane we find
that the dispersion in the RNB sample is not explained by chemical
evolution; the inferred bounds on lithium depletion from rotational mixing
are similar to those derived from models without chemical evolution. We
find that differences in the equivalent width measurements are primarily
responsible for different observational conclusions concerning the lithium
dispersion in halo stars. The standard Big Bang Nucleosynthesis predicted
lithium abundance which corresponds to the deuterium abundance inferred
from observations of high-redshift, low-metallicity QSO absorbers requires
halo star lithium depletion in an amount consistent with that from our
models of rotational mixing, but inconsistent with no depletion.
[Co-author: V.K. Narayanan]
Next: Ambruster, Carol
Up: No Title
Previous: Fleming, Tom
Cool Stars 12
2001-07-23