| Description |
Numerical simulations have suggested that giant molecular clouds (GMCs) can form from converging supersonic flows. In this scenario, the dynamics and chemistry of gas are strongly coupled and chemical processes, such as the HI-H2 and CII-CO transition, play an important role in the formation and evolution of GMCs. In particular, recent 3D magnetohydrodynamical simulations track both a detailed dynamical and chemical cloud evolution for the first time and find a significant scatter in the spatial distribution of CII and CO. This suggests that molecule formation is heavily affected by turbulence and is highly contradictory to what stationary photodissociation region (PDR) models predict. We propose to observe two boundary regions of the Perseus molecular cloud in the 158 micron fine structure line of CII using the Herschel HIFI instrument. Our proposal will test theoretical predictions from two different models (stationery vs turbulent) and address the importance of turbulence in the molecule formation. In addition, the proposed CII observations will allow us to explore the CO-dark gas in Perseus and to test the recent PDR model of the CO-dark gas in GMCs. The HIFI instrument will be critical to achieve our scientific goals as it provides the high enough spatial and velocity resolution to investigate the spatial distribution of CII in detail and to separate Perseus from foreground and background CII emission. |
