Lithium abundances from the 6104A line in cool Pleiades stars

TL;DR

This study measures lithium abundances in cool Pleiades stars using spectral lines at 6104A and 6708A, revealing significant scatter and potential effects of star spots, which complicate abundance determinations.

Contribution

It provides a comparative analysis of lithium abundances from two spectral lines and explores the impact of star spots on abundance measurements in Pleiades stars.

Findings

Significant scatter in lithium abundances from both spectral lines.

Correlation exists but with notable discrepancies in some stars.

Star spots may explain some abundance measurement differences.

Abstract

Lithium abundances determined by spectral synthesis from both the 6708A resonance line and the 6104 subordinate line are reported for 11 late-type Pleiades stars, including spectra previously analysed by Russell (1996). We report a 0.7 dex scatter in the abundances from 6708A, and a scatter at least as large from the 6104A line. We find a reasonable correllation between the 6104A and 6708A Li abundances, although four stars have 6104A-determined abundances which are significantly larger than the 6708-determined values, by up to 0.5 dex, suggesting problems with the homogeneous, one-dimensional atmospheres being used. We show that these discrepancies can be explained, although probably not uniquely, by the presence of star spots with plausible coverage fractions. The addition of spots does not significantly reduce the apparent scatter in Li abundances, leaving open the possibility that at least some of the spread is caused by real star-to-star differences in pre-main- sequence Li depletion.