THE H-ALPHA ENVIRONMENT OF T-TAURI RESOLVED BY SPECKLE INTERFEROMETRY

T Tauri, the prototype of a class of low-mass pre-main sequence stars, was observed with the 3.6m Canada-France-Hawaii telescope (CFHT) and the CP40 photon-counting camera in November 1989. The data have been analysed using techniques of Speckle Interferometry to obtain diffraction-limited information on the spatial extent of T Tauri in narrow passbands centered on the H alpha line and the nearby red continuum. The object appears unresolved in the continuum passband, while it is resolved in H alpha. The H alpha emission is fitted with a model consisting of two strongly flattened two-dimensional gaussians. In this model approximate to 80% of the flux lies in a component (A) which is only marginally resolved, and approximate to 20% lies in a component (B) with a semi-major axis FWHM of approximate to 0 ''.09. After subtraction of continuum, 2/3 of the H alpha emission is spatially unresolved and 1/3 is resolved. The position angle(1) of component B is 192 degrees +/- 5 degrees, which approximates the direction of the perpendicular to the jet known in the [OI] and [SII] lines; this jet extends 30 '' westwards up to the Herbig-Haro object HH1555. The corresponding linear size of the H alpha emitting region B is similar to 6 by 15 AU FWHM assuming a distance of T Tauri of d = 140pc. We argue that this emission arises either from the interaction between a weakly collimated wind with a circumstellar flaring disc, or from the basis of the westward jet which is seen on a larger scale.