  We have observed the bipolar jet from RW Aur A with STIS on board the HST.
After continuum subtraction, morphological and kinematic properties of this
outflow can be traced to within 0."1 from the source in forbidden emission
lines. The jet appears well collimated, with typical FWHMs of 20 to 30 AU in
the first 2" and surprisingly does not show a separate low-velocity component
in contrast to earlier observations. The systemic radial outflow velocity of
the blueshifted lobe is typically 50% larger than that of the redshifted one
with a velocity difference of about 65 km/s. Although such asymmetries have
been seen before on larger scales, our high spatial resolution observations
suggest that they are intrinsic to the "central engine" rather than effects of
the star's immediate environment. Temporal variations of the bipolar jet's
outflow velocities appear to occur on timescales of a few years. They have
combined to produce a 55% increase in the velocity asymmetry between the two
lobes over the past decade. In the red lobe estimated mass flux and momentum
flux values are around one half and one third of those for the blue lobe,
respectively. The mass outflow to mass accretion rate is 0.05, the former being
measured at a distance of 0."35 from the source.
