Identification of moving groups from a sample of B, A and F type stars.

Abstract

An algorithm to find moving groups has been developed and applied to a sample of 1924 B, A, and F main sequence stars, basically extracted from the Hipparcos Input Catalogue. This algorithm uses a non-parametric kernel estimator to describe the stellar distribution in a 4-dimensional space of velocities and age, although it can be used to detect the real clustering structure in an n-dimensional space automatically. Four moving groups near the Sun (Pleiades, Sirius, Hyades, IC 2391) have been identified without assuming any a priori knowledge of moving groups, neither the velocity distribution nor other physical properties. This provides objective evidence of the existence of the moving groups, and we find that about 26% of our sample belongs to such stellar streams. For the remaining field stars we obtain a mean motion of the Sun respect to the Local Standard of Rest (U,V,W)=(13.4+/-0.4, 11.1+/-0.3, 6.9+/-0.2)km/s.