New Lithium Measurements in Metal-Poor Stars

TL;DR

This study presents new lithium abundance measurements in 37 metal-poor stars using high-resolution spectroscopy, revealing rare Li-depleted stars and potential insights into Li depletion mechanisms.

Contribution

It provides the first high-quality Li measurements for many poorly-studied metal-poor stars, identifying rare Li-depleted stars and analyzing their properties.

Findings

Identification of two Li-depleted, moderately metal-poor stars.

Detection of line doubling in HIP 4754, indicating binarity.

Confirmation of the thinness of the Spite plateau in the sample.

Abstract

We provide *lambda*6708 Li 1 measurements in 37 metal-poor stars, most of which are poorly-studied or have no previous measurements, from high-resolution and high-S/N spectroscopy obtained with the McDonald Observatory 2.1m and 2.7m telescopes. The typical line strength and abundance uncertainties, confirmed by the thinness of the Spite plateau manifested by our data and by comparison with previous measurements, are <=4 mAng and <=0.07-0.10 dex respectively. Two rare moderately metal-poor solar-Teff dwarfs, HIP 36491 and 40613, with significantly depleted but still detectable Li are identified; future light element determinations in the more heavily depeleted HIP 40613 may provide constraints on the Li depletion mechanism acting in this star. We note two moderately metal-poor and slightly evolved stars, HIP 105888 and G265-39, that appear to be analogs of the low-Li moderately metal-poor subgiant HD 201889. Preliminary abundance analysis of G 265-39 finds no abnormalities that suggest the low Li content is associated with AGB mass-transfer or deep mixing and p-capture. We also detect line doubling in HIP 4754, heretofore classified as SB1.