Lithium in LP 944-20

TL;DR

This study provides a new, more accurate estimate of lithium abundance in the brown dwarf LP 944-20 using comprehensive spectral analysis, revealing significantly higher lithium levels than previously thought, with implications for brown dwarf properties.

Contribution

The paper introduces a self-consistent spectral analysis method that yields a higher lithium abundance estimate in LP 944-20, challenging previous measurements.

Findings

Lithium abundance in LP 944-20 is log N(Li) = 3.25 +/-0.25.

The lithium level is over two orders of magnitude higher than earlier estimates.

Dusty clouds do not affect the measured lithium abundance.

Abstract

We present a new estimate of the lithium abundance in the atmosphere of the brown dwarf LP 944-20. Our analysis is based on a self-consistent analysis of low, intermediate and high resolution optical and near-infrared spectra. We obtain log N(Li) = 3.25 +/-0.25 using fits of our synthetic spectra to the Li I resonance line doublet profiles observed with VLT/UVES and AAT/SPIRAL. This lithium abundance is over two orders of magnitude larger than previous estimates in the literature. In order to obtain good fits of the resonance lines of K I and Rb I and better fits to the TiO molecular absorption around the Li I resonance line, we invoke a semi-empirical model atmosphere with the dusty clouds located above the photosphere. The lithium abundance, however, is not changed by the effects of the dusty clouds. We discuss the implications of our estimate of the lithium abundance in LP 944-20 for the understanding of the properties of this benchmark brown dwarf.