  WR 25 is a colliding-wind binary star system comprised of a very massive
O2.5If*/WN6 primary and an O-star secondary in a 208-day period eccentric
orbit. These hot stars have strong, highly-supersonic winds which interact to
form a bright X-ray source from wind-collision-shocks whose conditions change
with stellar separation. Different views through the WR and O star winds are
afforded with orbital phase as the stars move about their orbits, allowing for
exploration of wind structure in ways not easy or even possible for single
stars. We have analyzed an on-axis Chandra/HETGS spectrum of WR 25 obtained
shortly before periastron when the X-rays emanating from the system are the
brightest. From the on-axis observations, we constrain the line fluxes,
centroids, and widths of various emission lines, including He-triplets of Si
XIII and Mg XI. We have also been able to include several serendipitous
off-axis HETG spectra from the archive and study their flux variation with
phase. This is the first report on high-resolution spectral studies of WR 25 in
X-rays.
