Galactic Orbits of Hipparcos Stars: Classification of Stars
  The Galactic orbits of 27 440 stars of all classes with accurate coordinates
and parallaxes of more than 3 mas from the Hipparcos catalogue, proper motions
from the Tycho-2 catalogue, and radial velocities from the Pulkovo Compilation
of Radial Velocities (PCRV) are analyzed. The sample obtained is much more
representative than the Geneva-Copenhagen survey and other studies of Galactic
orbits in the solar neighborhood. An estimation of the influence of systematic
errors in the velocities on orbital parameters shows that the errors of the
proper motions due to the duplicity of stars are tangible only in the
statistics of orbital parameters for very small samples, while the errors of
the radial velocities are noticeable in the statistics of orbital parameters
for halo stars. Therefore, previous studies of halo orbits may be erroneous.
The distribution of stars in selection-free regions of the multidimensional
space of orbital parameters, dereddened colors, and absolute magnitudes is
considered. Owing to the large number of stars and the high accuracy of PCRV
radial velocities, nonuniformities of this distribution (apart from the
well-known dynamical streams) have been found. Stars with their peri- and
apogalacticons in the disk, perigalacticons in the bulge and apogalacticons in
the disk, perigalacticons in the bulge and apogalacticons in the halo, and
perigalacticons in the disk and apogalacticons in the halo have been
identified. Thus, the bulge and the halo are inhomogeneous structures, each
consisting of at least two populations. The radius of the bulge has been
determined as 2 kpc.
