Discovery of Seven T Tauri Stars and a Brown Dwarf Candidatein the Nearby TW Hydrae Association

摘要: We report the discovery of five T Tauri star systems, two which are resolved binaries, in vicinity nearest known region recent formation: TW Hydrae Association. The newly discovered systems display same signatures youth (namely high X-ray flux, large Li abundance, and strong chromospheric activity) proper motion as original members. These similarities firmly establish group a bona fide association, unique its proximity to Earth complete isolation from any molecular clouds. At an age ~10 Myr distance ~50 pc, association members excellent candidates for future studies circumstellar disk dissipation formation brown dwarfs planets. Indeed, example, our speckle imaging revealed faint, very likely companion 2'' north CD -33° 7795 (TWA 5). Its color brightness suggest spectral type ~M8.5 which, at ~107 yr, implies mass ~20MJup.