Radio Proper Motions of Wolf-Rayet Stars
  We present the analysis of observations taken from the Very Large Array
archive of six Wolf-Rayet stars with radio emission, with the purpose of
determining their proper motions. Typically, these observations cover periods
of 10 to 20 years. To verify the method, we included WR 140 in the sample,
finding that the proper motions determined by us are a few times more accurate
than and consistent within noise with those of Hipparcos. The other five WR
stars were not studied by Hipparcos and we report their proper motions for the
first time. The proper motions for WR 145a = Cyg X-3 are consistent with the
source being stationary with respect to its local standard of rest and suggest
that the black hole in this binary system formed by direct collapse of a
massive star, without expulsion of a supernova remnant.
