Dust evolution in the interstellar medium

Dust grains play a crucial role in many physical and chemical processes in the interstellar medium (ISM) and in protoplanetary disks (PPDs).

In the ISM, dust properties influence, for example, the formation and temperature of the major molecules in molecular clouds. It is therefore important to characterise the grain size, structure, shape and material composition in all phases of the ISM. Observations of the dust SED and extinction give indication of the dust properties and how these properties change towards denser regions. Compared to the diffuse ISM the observed SEDs of these denser regions show a decrease in colour temperature, increase in spectral index and increase in emissivity at 250 μm. Based on the THEMIS dust model, these observations can be explained self-consistently with coagulation and accretion processes of dust in regions with Av<16. These evolutionary processes can also explain the observed core- and cloud-shine. In conclusion, the evolutionary processes and especially grain growth begins in denser regions of the ISM.

05/10/2017 - 12:30
Dr. Melanie Köehler
Queen Mary University of London ,UK