The evolutionary stage of the Herbig Ae/Be stars in the R Coronae Australis star-forming region.

Data obtained with the IRAS and ground-based telescope are used to construct and analyze the spectral energy distribution of the premain-sequence stars HD 176386, TY CrA, R CrA, and T CrA. For all stars two possible models, one based on a normal extinction law and another one with an extinction law characterized by R greater than 3.1, are considered. Only the latter model is found to be acceptable. HD 176386 and TY CrA have excess radiation in the FIR only. This excess is caused by rather cool dust (about 95 K) located at a significant distance from the central star (up to about 1000 AU). R CrA and T CrA have excess radiation not only in the FIR but in the near-IR as well. Analysis of the properties of these hot dust shells, based on a spherical symmetric model, indicate large particles of iron and/or graphite to be the most likely constituents.