Testi et al. All star formation theories require the existence of circumstellar disks for the interchange of mass and angular momentum between the central object and the parent cloud. In their compilation Natta et al. In order to distinguish between these scenarios, interferometric observations of the dust continuum emission are required. Energetic molecular outflows have been detected in massive and low-mass protostars.
Significant differences exist between massive and low-mass outflows.
The nice bipolar morphology observed in many low-mass stars is not found toward many massive star outflows. Massive star outflows seem less collimated and more chaotic than those of low-mass stars. In order to determine the characteristics and time-scales of massive outflows it is important to study outflows in different evolutionary stages. Since clustering is important in massive stars, interferometric observations are required to avoid confusion with other possible outflows powered by infrared and millimeter companions. Furthermore, we found that there is a clear correlation between the spatial distribution of the dense gas around the stars and the ages of the stars.