Protostellar outflow shocked regions: astrochemical laboratories at our disposal - The case of L1157

Chemical compounds, and in particular organic molecules, have been observed and are thought to be formed during all stages of star formation. Among the ~320 species that have been detected in the ISM to date, we are particularly interested in the so-called interstellar complex organic molecules (iCOMs), which are carbonaceous molecules containing ≥6 atoms, of which at least one is other than C or H. It is currently thought that there are two possible ways for these iCOMs to form: on the surface of dust grains, or in the gas phase, the latter of which we are interested in here. To study the evolution of organic chemistry in the gas phase, we are targeting the protostellar stage, during which supersonic ejection processes (≥100 km/s) from the central object cause the formation of shocked regions. These shocks are the siege of a very specific chemistry, as radicals and species previously trapped on dust grains, frozen mantles or in the core are released into the gas phase, where we can observe them and where they can react to form new molecules. We focus on the study of the molecular outflow driven by the protobinary L1157-mm, which has three shocked regions of different and well constrained ages. Observations of these three regions with the NOEMA interferometer allow us to study the evolution of the gas-phase chemistry with time. Finally, gas-phase chemical modeling of the source, coupled with the observations, gives us an additional understanding of how the detected iCOMs form