Halos around Herbig Ae/Be stars -: more common than for the less massive T Tauri stars

We present sub-arcsec observations of a sample of 31 Herbig Ae/Be and related stars obtained with the technique of near-infrared speckle interferometry. In 18 of the 31 stars we find evidence for circumstellar halos. These halos have a typical size of 1.1 , corresponding to approximate to 1000 AU at the distances of the objects. Most of the halos have blue colours, hence are seen in scattered light. The incidence of observable circumstellar matter is significantly higher than in a larger sample of T Tauri stars observed with the same technique (Leinert et al. 1993a). We suggest that this difference results as a consequence of a faster initial evolution of the more massive Herbig Ae/Be stars. The near-infrared halos found in our study appear to correspond to the envelopes invoked to model the strong mid-infrared excesses of Herbig Ae/Be stars.