  We modelled the Chandra and RXTE X-ray spectra of the massive binary WR 140
in the framework of the standard colliding stellar wind (CSW) picture. Models
with partial electron heating at the shock fronts are a better representation
of the X-ray data than those with complete temperature equalization. Emission
measure of the X-ray plasma in the CSW region exhibits a considerable decrease
at orbital phases near periastron. This is equivalent to variable effective
mass-loss rates over the binary orbit. At orbital phases near periastron, a
considerable X-ray absorption in excess to that from the stellar winds in WR
140 is present. The standard CSW model provides line profiles that in general
do not match well the observed line profiles of the strong line features in the
X-ray spectrum of WR 140. The variable effective mass-loss rate could be
understood qualitatively in CSW picture of clumpy stellar winds where clumps
are efficiently dissolved in the CSW region near apastron but not at
periastron. However, future development of CSW models with
non-spherically-symmetric stellar winds might be needed to get a better
correspondence between theory and observations.
