Space motions of K3--M2 dwarfs in the solar neighborhood

Space motions have been determined from parallaxes, proper motions, and radial velocities of 62 dwarfs with B - V color indices between +0.95 and + 1.55 (corresponding to K3 V and M2 V on the MK classification system). The precision and homogeneity in all of the observations and the absence of a selection effect favoring high-velocity stars allow a sample to be defined which is more truly representative of K-M dwarfs in the solar vicinity than has been heretofore possible. In the past, samples have been comprised mostly of stars listed in the Vale Generat Calatog of Trigonornefric Stettar Parattazes. Such a sample is the one of Kron, Gascoigne, and White, which is shown to incorporate a disproportionately large number of high-velocity stars as indicated by their space motions. However, the main sequence which it defines is not significantly different from that of the stars included here. An analysis of the space motions of our K3-M2 dwarfs yields 18.0 km 1 for the solar motion with apex at 19h48 (297 ), + 53 (1950). The U-, V-, and W-axes of the velocity ellipsoid are 28.7,19.1, and 15.1 km 1, respectively and the vertex deviation is l6 . These results are compared with earlier analyses; agreement is close only for the more recent ones which take velocity selection effects into account.