Lithium in the Upper Centaurus Lupus and Lower Centaurus Crux Subgroups of Scorpius-Centaurus

TL;DR

This study measures lithium abundances in young stars of the Scorpius-Centaurus OB association using spectral lines, finding minimal intrinsic scatter and favoring the subordinate line for accurate abundance determination.

Contribution

It demonstrates that the ext{Li} I ext{ } ext{6104} line provides more consistent lithium abundance measurements than the ext{6708} doublet in young stars.

Findings

Li scatter limited to ~0.15 dex in studied stars

The ext{6104} line yields less scatter than the ext{6708} line

The subordinate line is preferred for young, Li-rich stars with ext{T}_{ ext{eff}} ≥ 5200 K

Abstract

We utilize spectroscopically derived model atmosphere parameters and the \ion{Li}{1} $\lambda6104$ subordinate line and the $\lambda6708$ doublet to derive lithium abundances for 12 members of the Upper-Centaurus Lupus (UCL) and Lower-Centaurus Crux (LCC) subgroups of the Scorpius Centaurus OB Association. The results indicate any intrinsic Li scatter in our 0.9-1.4 $M_{\odot}$ stars is limited to ${\sim}0.15$ dex, consistent with the lack of dispersion in ${\ge}1.0$ $M_{\odot}$ stars in the 100 Myr Pleiades and 30-50 Myr IC 2391 and 2602 clusters. Both ab initio uncertainty estimates and the derived abundances themselves indicate that the $\lambda$6104 line yields abundances with equivalent or less scatter than is found from the $\lambda$6708 doublet as a result of lower uncertainties for the subordinate feature, a result of low sensitivity to broadening in the subordinate feature. Because NLTE corrections are less susceptible to changes in surface gravity and/or metallicity for the 6104 {\AA} line, the subordinate Li feature is preferred for deriving lithium abundances in young Li-rich stellar association stars with $T_{\rm eff}{\ge}5200$ K.