CO and HC3N maps of IRAS 20050+2720

Two of them, OVRO 1 and OVRO 2, have also been detected at 7mm. OVRO 3, which is located close to the C18O emission peak, could be associated with IRAs 20050+2720. The mass of the sources, estimated from the dust continuum emission, is 6.5M_{sun}_ for OVRO 1, 1.8M_{sun}_ for OVRO 2, and 1.3M_{sun}_ for OVRO 3.

The CO (1-0) emission traces two bipolar outflows within the OVRO field of view, a roughly east-west bipolar outflow, labeled A, driven by the intermediate-mass source OVRO 1, and a northeast-southwest bipolar outflow, labeled B, probably powered by a YSO engulfed in the circumstellar envelope surrounding OVRO 1. The multiplicity of sources observed towards IRAS 20050+2720 appears to be typical of intermediate-mass protostars, which form in dense clustered environments.

In some cases, as for example IRAS 20050+2720, intermediate- mass protostars would start forming after a first generation of low-mass stars has completed their main accretion phase. The properties of intermediate-mass protostars and their outflows are not significantly different from those of low-mass stars. Although intermediate-mass outflows are intrinsically more energetic than those driven by low-mass YSOs, they do not show intrinsically more complex morphologies when observed at high angular resolution.

Known intermediate-mass protostars do not form a homogeneous group. Some objects are likely in an earlier evolutionary stage as suggested by the infrared emission and the outflow properties.