  High-resolution X-ray spectra of SS 433 obtained after a binary egress with
the Chandra High Energy Transmission Grating Spectrometer (HETGS) were studied.
Many Doppler-shifted X-ray emission lines from highly ionized elements were
detected. The initial temperature of the jets is estimated to be 20 keV. The
lines are found to generally be broader than the instrumented resolution. The
widths of the Fe XXV K-alpha and Si XIII K-alpha lines correspond to velocity
dispersions of 2100 (+600/-340) km/s and 840 (+180/-150) km/s respectively, in
terms of Gaussian sigma. Neither the measured line widths nor their dependence
on the atomic number can be explained by thermal broadening alone. Alternative
explanations of the observed line widths are discussed, including in particular
a progressive jet collimation along its axis.
