  A two-dimensional velocity distribution in the UV-plane has been obtained for
stars in the solar neighbourhood, using the Hipparcos astrometry for over 4000
survey stars with parallaxes greater than 10 mas and radial velocities found in
the Hipparcos Input Catalogue. In addition to the already known grouping
characteristics (field stars plus young moving groups), the velocity
distribution seems to exhibit a more complex structure characterized by several
longer branches running almost parallel to each other across the UV-plane. By
using the wavelet transform technique to analyse the distribution, the branches
are visible at relatively high significance levels of 90 per cent or higher.
They are roughly equidistant with a separation of about 15 km/s for early-type
stars and about 20 km/s for late-type stars, creating an overall quasi-periodic
structure which can also be detected by means of a two-dimensional Fourier
transform. This branch-like velocity distribution might be due to the galactic
spiral structure.
