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

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.

to appear in the proceedings of the conference 'Brown dwarfs come of age', May 20-24 2013, Memorie della Societa Astronomica Italiana