Characterization of the Twa22 AB system. A new calibrator for evolutionary tracks?

¹ Laboratoire d'Astrophysique de Grenoble, BP. 53, 38041 Grenoble Cedex 9, France
² ESO, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19, Chile
³ Department of Physics and Astronomy, Center for Astrobiology, University of California, Los Angeles, California 90095, USA
⁴ CRAL-ENS, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
⁵ Science Center/Caltech, M/S 220-6, 1200 E. California Blvd., Pasadena, CA 91125, USA

Corresponding authors: mickael.bonnefoy@obs.ujf-grenoble.fr ; cdumas@eso.org ; ben@astro.ucla.edu ; fallard@ens-lyon.fr ; song@ipac.caltech.edu

Abstract

Tight binaries discovered in young nearby associations are ideal targets to provide dynamical mass measurments through orbital monitoring. Coupled with estimated temperatures, surface gravities and luminosities, direct mass measurments provide benchmarks for evolutionary models of low-mass stars (M ≤ 0.5 M_๏) and brown dwarfs (M ≤ 0.078 M_๏) at young ages (Age ≤ 100 Myrs). TWA22 AB is likely to be a member of the nearby TW Hydrae association (Age ~ 8 Myr). It was resolved in a tigh binary with a projected separation of a few AU. In this paper we present preliminary results on the companion orbital monitoring and on the spectral characterisation of the system.