  Suzaku observations of the Wolf-Rayet binary WR 140 (WC7pd+O5.5fc) were made
at four different times around periastron passage in 2009 January. The spectra
changed in shape and flux with the phase. As periastron approached, the column
density of the low-energy absorption increased, which indicates that the
emission from the wind-wind collision plasma was absorbed by the dense W-R
wind. The spectra can be mostly fitted with two different components: a warm
component with kT=0.3--0.6 keV and a dominant hot component with kT~3 keV. The
emission measure of the dominant, hot component is not inversely proportional
to the distance between the two stars. This can be explained by the O star wind
colliding before it has reached its terminal velocity, leading to a reduction
in its wind momentum flux. At phases closer to periastron, we discovered a cool
plasma component in a recombining phase, which is less absorbed. This component
may be a relic of the wind-wind collision plasma, which was cooled down by
radiation, and may represent a transitional stage in dust formation.
