Max Planck Institute for Extraterrestrial Physics
Astrochemistry of pre-stellar cores: the deuteration maps of H2CS towards L1544
Low-mass stars like the Sun are the product of the gravitational contraction of pre-stellar cores, which form within molecular clouds. Pre-stellar cores provide the initial conditions in the process of star and planet formation, thus their study is needed to put constraints on theories. Deuteration is a crucial tool to understand the complexity of interstellar chemical processes, especially when they involve the interplay of gas and surface. In the case of multiple deuteration even more so. While Sulfur is not depleted in the diffuse Interstellar Medium (ISM), only a small fraction of the cosmic abundance is observed in dense cores, suggesting that the sulfur might be depleted on the grains. However, it is still unclear in which molecular form. I will present single dish observations of molecular emission maps of H2CS, HDCS and D2CS towards the pre-stellar core L1544 with the IRAM 30 m telescope. These data allow us to compute the deuteration maps of H2CS across the core and hence study where the deuteration is more efficient. With this dataset we are able to test current gas–dust chemical models involving Sulfur and Deuterium in dense cores. I will present our results, and discuss the role the SOFIA will play to understand deuterium fractionation in star-forming regions.