10 AU SCALE HALO STRUCTURE AROUND DG TAURI

Lunar occultation observations of the active T Tauri star DG Tau show that in the infrared K band it has a core-halo structure: 20%-25% of the flux comes from a region 10 AU in extent and the rest from an unresolved core smaller than an AU. These results are consistent with those reported by Leinert et al. from a separate observation. Our results and those of Leinert et al., measuring the intensity distribution projected along directions spanning roughly 40-degrees, indicate that the resolved structure is not highly elongated. We interpret the extended emission as star light scattered by optically thin dust located in a halo surrounding the star. The total mass of the dust in the halo is only a very small fraction of that in the optically thick disk but is sufficient to produce the silicate absorption and polarization observed in this star.