Meridional Circulation II: A Unified Mechanism for Lithium Depletion in Solar Analogs and the Lithium Dip in Mid-F Cluster Stars

TL;DR

This paper presents a unified model based on meridional circulation-driven mixing that explains lithium depletion patterns in solar analogs and the Li dip in mid-F stars, aligning with many observed features but with some limitations.

Contribution

It extends a previous mixing framework to main sequence stars, successfully reproducing observed lithium trends in solar analogs and partially explaining the Li dip in mid-F stars.

Findings

Models reproduce the Li-Age correlation in solar analogs.

Good agreement between simulated and observed Li-T_eff relationships.

Partial explanation of the Li dip, with some limitations due to rotation velocity distribution.

Abstract

The behavior of lithium (Li) in Population I main sequence stars challenges standard stellar theory. Two phenomena stand out: the solar Li problem which extends to Li depletion in solar analogs and the Li dip observed in mid-F stars within open clusters. Building on the meridional circulation-driven radial mixing framework previously developed to explain Li-enriched red clump stars, we explore its relevance to Li depletion on the main sequence. First, our models reproduce the observed $A(\text{Li})$-Age correlation in solar analogs. Through detailed isochrone analysis, we find good agreement between the simulated and observed $A(\text{Li})$-$T_{\text{eff}}$ relationships within the solar analog parameter space. However, the predicted solar Li abundance ($\sim 1.5\,\text{dex}$) is still higher than current solar measurements. Second, our models partially explain the Li dip phenomenon in mid-F cluster stars. The models accurately reproduce Li distributions on the cool side of the Li dip in most clusters and capture the Li behaviors on the hot side observed in systems like the Hyades. However, we identify limitations in the models' ability to fully reproduce the dip morphology, particularly due to the rotation velocity distribution of sample stars in this temperature zone.