X-Shooter spectroscopy of brown dwarfs in the TW Hya association

TL;DR

This study uses X-Shooter spectra to analyze four brown dwarfs in the TW Hya association, examining their stellar parameters, chromospheric activity, and accretion rates across different evolutionary stages.

Contribution

First detailed spectroscopic analysis of brown dwarfs in TW Hya covering both diskless and accreting objects, providing insights into their evolution and accretion processes.

Findings

Determined stellar parameters for two diskless brown dwarfs.

Estimated mass accretion rates for two accreting brown dwarfs.

Analyzed chromospheric emission line spectra of the targets.

Abstract

We present broad-band mid-resolution X-Shooter/VLT spectra for four brown dwarfs of the TW Hya association. Our targets comprise substellar analogs representing the different evolutionary phases in young stellar evolution: For the two diskless brown dwarfs, TWA-26 and TWA-29, we determine the stellar parameters and we study their chromospheric emission line spectrum. For the two accreting brown dwarfs, TWA-27 and TWA-28, we estimate the mass accretion rates from empirical correlations between emission line luminosities and the accretion luminosity.