Chromospheric activity, lithium and radial velocities of single late-type stars possible members of young moving groups

We present here high resolution echelle spectra taken during three observin g runs of 14 single late-type stars identified in our previous studies (Mon tes et al. 2001b, hereafter Paper I) as possible members of different young stellar kinematic groups (Local Association (20-150 Myr), Ursa Major group (300 Myr), Hyades supercluster (600 Myr), and IC 2391 supercluster (35 Myr )). Radial velocities have been determined by cross correlation with radial velocity standard stars and used together with precise measurements of pro per motions and parallaxes taken from Hipparcos and Tycho-2 Catalogues, to calculate Galactic space motions (U, V, W) and to apply Eggen's kinematic c riteria. The chromospheric activity level of these stars have been analysed using the information provided for several optical spectroscopic features (from the CaII H & K toCaII IRT lines) that are formed at different heights in the chromosphere. The Li I lambda 6707.8 Angstrom line equivalent width (EW) has been determined and compared in the EW(Li I) versus spectral type diagram with the EW(Li I) of stars members of well-known young open cluste rs of different ages, in order to obtain an age estimation. All these data allow us to analyse in more detail the membership of these stars in the dif ferent young stellar kinematic groups. Using both, kinematic and spectrosco pic criteria we have confirmed PW And, V368 Cep, V383 Lac, EP Eri, DX Leo, HD 77407, and EK Dra as members of the Local Association and V834 Tau, pi ( 1) UMa, and GJ 503.2 as members of the Ursa Major group. A clear rotation-a ctivity dependence has been found in these stars.