The IC1396N proto-cluster at a scale of ∼250 AU

Aims.We investigate the mm-morphology of IC 1396 N with unprecedented spatial resolution to analyze its dust and molecular gas properties, and draw comparisons with objects of similar mass. Methods: We have carried out sensitive observations in the most extended configurations of the IRAM Plateau de Bure interferometer, to map the thermal dust emission at 3.3 and 1.3 mm, and the emission from the J=13_k→ 12k hyperfine transitions of methyl cyanide (CH3CN). Results: We unveil the existence of a sub-cluster of hot cores in IC 1396 N, distributed in a direction perpendicular to the emanating outflow. The cores are embedded in a common envelope of extended and diffuse dust emission. We find striking differences in the dust properties of the cores (β≃ 0) and the surrounding envelope (β≃ 1), very likely testifying to differences in the formation and processing of dust material. The CH3CN emission peaks towards the most massive hot core and is marginally extended in the outflow direction. Based on observations obtained at the IRAM Plateau de Bure Interferometer (PdBI). IRAM is funded by the Centre Nationale de la Recherche Scientifique (France), the Max-Planck Gesellschaft (Germany), and the Instituto Geografico Nacional (Spain).