2002ApJ...564..834W

We present the results of Hubble Space Telescope Wide Field Planetary Camera (WFPC2) observations of FS Tau and its environment obtained in the narrowband emission line filters Hα and [S II] λλ6716,6731 Å. Based on these data the morphology of line emission within this region can be studied on a size scale of 0".1 for the first time. Despite the fact that FS Tau A has strong forbidden emission lines, there is no evidence for extended emission at these wavelengths beyond 0".5 from the components of this close T Tauri binary system. In the FS Tau B outflow, interesting morphological properties can be studied at high spatial resolution. In this jet we find a fine structure where circular or elliptical jet knots are correlated with minima of the jet width. The overall width of this jet decreases with distance from the source. The FS Tau B jet is thus a rare example of a jet which may be recollimated far away from its source. The jet is much more prominent in Hα than in [S II], while the counterjet shows the opposite behavior. The line ratio Hα/[S II] increases with lateral distance from the jet axis, which is indicative of entrainment of ambient material.