Submillimeter Astronomy

The deeply embedded stages are particularly important for our understanding of the star formation process. The evolution of a protostar through these embedded stages is likely to affect the properties of the emerging star; its final mass depends, e.g., on the amount of material accreted in this phase. It is in these deeply embedded stages that the seeds for planets are planted: circumstellar disks are formed early in the evolution of protostars because material falling in from the larger scale envelope, due to its angular momentum, cannot accrete directly to the central star and piles up in a circumstellar disk. The properties of the emerging disks reflect the physical and chemical structure of the innermost regions of the centrally condensed envelopes that surround the protostars, but it remains an open question when they form and how rapidly they grow in size.

It is therefore important to zoom in and resolve the solar system scales of low-mass stars in these early stages of their evolution - and thus also trace the physical and chemical evolution of matter from the natal core to the protoplanetary disk. Our group tries to do this through observations and modeling of the physical and chemical properties of young stars and their disks in the earliest evolutionary stages. For this we in particular rely on observations at infrared and submillimeter wavelengths. At these wavelengths we can penetrate the molecular clouds and protostellar cores and probe the highly extincted inner regions where planets may be forming.

Over the next decade the Atacama Large Millimeter Array (ALMA) is therefore going to be the key facility for star formation research. ALMA will revolutionize studies of deeply embedded protostars by probing scales as small as 0.01" (a few AU at the distances of nearby star forming regions), thereby resolving the chemical and dynamical structure of disks at the time when planets start to form. Its high sensitivity will furthermore allow us to explore the formation of solar-type stars as a function of environment by studying the properties of individual low-mass protostars in massive star forming regions and even nearby galaxies. This will lead to a new understanding of the importance of environment for the properties of emerging stars, disks, and planets.