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OATS-DAUT SEMINAR
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Speaker:
Giancarlo Pace (ARIES, Nainital, India)
Title:
The cosmological lithium discrepancy and how
observations in open clusters can be of some help
Date: Wednesday, December 5th, 2007
Time: 12:00
Venue: Villa Bazzoni
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Abstract:
Lithium is one of the few elements produced during
the Big Bang, and then it is mostly destroyed in stars. The primordial
lithium abundance have been estimated by means of: a) Big Bang
nucleosynthesis models combined with WMAP observations; and b)lithium
abundances in old, pop II stars, more precisely those in the so called
Spite plateau. The two estimations differ of a factor two.
This factor, when compared to the enormous range that lithium
abundance in Galactic objects spans (two order of magnitude from the
Sun to the interstellar medium) is widely considered an important
confirmation that both cosmological standard models and stellar
abundance determinations have sound basis. And yet an explanation has
to be found for it: is the Big Bang nucleosynthesis model to be
corrected, or is the atmospheric content of Spite plateau stars
different from the primordial one? Both hypothesis have been suggested
in the literature. Who is right? After extensively reviewing this
topic, I will speak about the role of observations in open clusters in
solving the dilemma, an observation campaing and the latest results of
Randich, Pace, Pastori and Bragaglia on the old open cluster Berkley
32.
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contact: Simone Recchi (OATS)