  The nearby TW Hydrae Association (TWA) is currently a benchmark for the study
of formation and evolution of young low-mass stars, circumstellar disks and the
imaging detection of planetary companions. For such studies, it is crucial to
evaluate the distance to group members in order to access their physical
properties. Membership of several stars is strongly debated and age estimates
vary from one author to another with doubts about coevality. We revisit the
kinematic properties of the TWA in light of new trigonometric parallaxes and
proper motions to derive the dynamical age of the association and physical
parameters of kinematic members. Using observations performed with the NTT/ESO
telescope we measured trigonometric parallaxes and proper motions for 13 stars
in TWA. With the convergent point method we identify a co-moving group with 31
TWA stars. We deduce kinematic distances for 7 members of the moving group that
lack trigonometric parallaxes. A traceback strategy is applied to the stellar
space motions of a selection of 16 of the co-moving objects with accurate and
reliable data yielding a dynamical age for the association of t = 7.5 +/- 0.7
Myr. Using our new parallaxes and photometry available in the literature we
derive stellar ages and masses from theoretical evolutionary models. With new
parallax and proper motion measurements from this work and current astrometric
catalogs we provide an improved and accurate database for TWA stars to be used
in kinematical analysis. We conclude that the dynamical age obtained via
traceback strategy is consistent with previous age estimates for the TWA, and
is also compatible with the average ages derived in the present paper from
evolutionary models for pre-main sequence stars.
