Pre-MS depletion, accretion and primordial 7Li
P. Molaro (1), A. Bressan (2), M. Barbieri (3), P. Marigo (4), S., Zaggia (3),((1) INAF-Osservatorio Astronomico di Trieste, (2) SISSA, Trieste,, (3) INAF-Osservatorio Astronomico di Padova, (4) Dipartimento di Fisica e, Astronomia. Universit\`a degli Studi di Padova)

TL;DR
This paper explores how pre-main sequence lithium depletion, combined with accretion processes and overshoot mixing, can explain observed lithium abundances in stars and stellar populations, challenging traditional views.
Contribution
It introduces a model where pre-MS lithium destruction is followed by accretion, accounting for observed lithium levels and explaining discrepancies in stellar lithium abundances.
Findings
Pre-MS lithium depletion can be offset by accretion restoring lithium levels.
Overshoot mixing significantly enhances lithium destruction during pre-MS.
The model explains the lithium abundance variations in different stellar populations.
Abstract
We reconsider the role of pre-main sequence (pre-MS) Li depletion on the basis of new observational and theoretical evidence: i) new observations of Halpha emissions in young clusters show that mass accretion could be continuing till the first stages of the MS, ii) theoretical implications from helioseismology suggest large overshooting values below the bottom of the convective envelopes. We argue here that a significant pre-MS 7Li destruction, caused by efficient overshoot mixing, could be followed by a matter accretion after 7Li depletion has ceased on MS thus restoring Li almost to the pristine value. As a test case we show that a halo dwarf of 0.85 Msun with an extended overshooting envelope starting with an initial abundance of A(Li) = 2.74 would burn Li completely, but an accretion rate of the type 1e-8xe^{-t/3e6} Msun yr would restore Li to end with an A(Li) = 2.31. A…
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Taxonomy
TopicsStellar, planetary, and galactic studies · Astrophysics and Star Formation Studies · Astro and Planetary Science
