Contribution Invited Talk
The Physical and Chemical Structure of Infrared-Dark Clouds
Observations at mid-IR and far-IR wavelengths have revealed that the ISM in our Galaxy is highly organised in cold and dense filamentary structures. The most massive of these structures are called Infrared-Dark Clouds (or IRDCs) and are believed to be the initial conditions of massive star and star cluster formation. In the past decade, a large effort has been made to determine the global physical properties of these clouds and of their dense and cold clumps/cores. However, it remains poorly understood how IRDCs form and subsequently fragment into denser sub-structures. In this talk, I will show how molecular line studies of IRDCs have enhance our understanding of the internal physical structure and gas dynamics of these clouds, and how chemistry can be used to distinguish between different scenarios of molecular cloud and star cluster formation.