CORONOGRAPHIC IMAGING OF T-TAURI - DISCOVERY OF AN OPTICAL JET IN BURNHAM NEBULA

We present coronographic images of T Tauri and its surrounding nebula (Burnham nebula) obtained with the STScI coronograph at Calar Alto (Spain) and with the STScI-Torino coronograph at ESO-NTT in H alpha 6563, [SII] 6716-6731 and 6670/80 Angstrom satellite continuum filters. Taking advantage of the subarcsec seeing conditions, we mapped the circumstellar environment down to 2'' from the star, corresponding to 320 A.U. at the T Tauri distance of 160 pc. Both the H alpha and [SII] images reveal a complex morphology, characterized by several clumps of shock-excited gas superimposed on large scale continuum emission. In particular, we detected a jet-like feature departing from the immediate surroundings of the star in a southly direction that leads to a region of shock excited clumps. A curved filament departs from this region, crossing Burnham nebula up to the previously known Herbig-Haro object HH A (Schwartz 1990). The south-western part of Burnham nebula is characterized by a number of small, nearly circular clumps. A faint, isolated HH object is also present in the northern part of the nebula. Taking into account all the available data, we suggest that the optical jet is emitted by TTau S roughly along the plane of the sky. The jet at first moves into the neutral components originating the shock excited knots and then impacts with the edges of the cavity associated to the outflows. The jet wiggling due to the orbital motion of the emitting source and/or to precession phenomena could explain the peculiar excitation status of the Burnham nebula.