1995A&A...300..181D

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 Hα line and the nearby red continuum. The object appears unresolved in the continuum passband, while it is resolved in Hα. The Hα emission is fitted with a model consisting of two strongly flattened two-dimensional gaussians. In this model ∼80% of the flux lies in a component (A) which is only marginally resolved, and ∼20% lies in a component (B) with a semi-major axis FWHM of ∼0.09". After subtraction of continuum, 2/3 of the Hα emission is spatially unresolved and 1/3 is resolved. The position angle of component B is 192deg±5deg, 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 Hα emitting region B is ∼6 by 15AU 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.