CHARACTERIZATION OF THE TWA22 AB SYSTEM. A NEW CALIBRATOR FOR EVOLUTIONARY TRACKS?

摘要

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 evo-lutionary 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 prelimi-nary results on the companion orbital monitoring and on the spectralcharacterisation of the system.