Lunar occultation and near-infrared speckle observations of DG Tauri, FV Tauri, FW Tauri and GG Tauri.

Results are presented of near-infrared lunar occultation observations at 2.2 microns. It is demonstrated that DG Tau has a 'shell' with a diameter of 6.8 AU (FWHM). A 1D projected image of this circumstellar structure is reconstructed. Follow-up near-infrared speckle observations show a halo with a diameter of 130 AU, which is probably the outward extension of the inner 'shell'. Our speckle measurements also show both GG Tau and its nearby companion GG Tau/c to be double, possibly forming a hierarchical quadruple system. The duplicity of FV Tau and FW Tau found in previous lunar occultation observations by Chen et al. (1990) is confirmed. The projected positions of the companions of FV Tau and FW Tau are determined. No duplicity or extended components were detected in the cases of DL Tau, GU Tau, and IRAS 04212 + 2610.