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Chemistry in regions of star formation (Objectives)

The process of star formation begins with the slow diffusion of the neutrals with respect to the ions under the influence of self gravity, which will lead to a gradual loss of the supporting magnetic field and brings dark cloud cores to the brink of collapse. The degree of ionization is controlled by large molecules, which provide efficient neutralization channels. During the subsequent collapse phase, cooling by molecular species - specifically H$_2$O - is of key importance in regulating the energy balance of the surrounding gas and hence the thermal support. In turn, the newly formed star directly influences the chemical composition of its environment. In the dark cloud core, ion-molecule chemistry dominates the formation of molecules and hence the chemical composition is directly linked to the degree of ionization. After the star formation process has commenced, in the warm gas, directly surrounding the protostar, neutral-neutral reactions convert simple molecules (such as alcohols) into more complex ones (such as ethers and esters). The protostar also drives strong shock waves into its surrounding which affects the composition of its environment. Observationally, SO, SO$_2$ and SiO are known to be indicators of shock activity. At the same time, far-ultraviolet photons ( $\buildrel > \over \sim $6eV) from the newly formed star break down small molecules into radicals and ions. At the same time, neutral-neutral reactions drive the chemistry towards complexity in the circumstellar disk surrounding the protostar. All of these processes will influence the chemical reservoir available to the planets that may form in this environment. The network will explore all aspects of chemistry in star forming regions starting from dark cloud cores, through their slow ambipolar contraction phase, their gravitational collapse phase, the formation and evolution of a circumstellar planetary disk, to the eventual disruption of the cloud by the newly formed star. The network will employ experimental studies on relevant reactions and their products, quantum chemical studies, supported by laboratory studies, on the excitation characteristics of the species formed this way, and astronomical models including detailed radiative transfer in these molecular lines. We anticipate a major breakthrough for the following questions: