Search for circumstellar disks around Herbig Be stars

We have carried out a high-sensitivity search for circumstellar disks around Herbig Be stars in the continuum at 1.3 mm and 2.7 mm using the IRAM interferometer at the Plateau de Bure (PdBI). We report data on three Herbig Be stars MWC 1080, MWC 137 and R Mon. We have observed two of them, MWC 137 and R Mon, in the continuum at 0.7 cm and 1.3 cm using the NRAO Very Large Array (VLA). This allows us to build the complete SED at mm and cm wavelengths and fit a simple disk model. We report the detection of circumstellar disks around MWC 1080 with M-d = 0.003M(.) and R Mon with M-d = 0.01M(.). A significant upper limit to the mass of the circumstellar disk around MWC137 has been obtained. Our results show that the ratio M-d/ M* is at least an order of magnitude lower in Herbig Be stars than in Herbig Ae and T Tauri stars.