Vianney Taquet (University of Leiden)
Thursday February 4th - 11am
IPAG Seminar Room - IPAG
The early phases of star formation are accompanied by a process of chemical complexity. Several Complex Organic Molecules (COMs), molecules based on carbon chemistry and with more than 5 atoms, have been detected in large quantities around high-mass and low-mass protostars for several decades. The current scenario for the formation of these COMs, potentially at the origin of the prebiotic chemistry seen in our Solar System, is based on UV-induced warm grain surface chemistry occurring in the envelopes surrounding protostars followed by ice evaporation in their so-called hot cores or hot corinos. I will present new observations of COMs towards star-forming regions at different evolutionary stages that challenge this scenario. COMs have recently been detected in cold dark clouds and cores shielded by strong UV irradiation, where UV-induced warm surface chemistry does not apply, while the high abundances of several COMs derived in the hot cores of low-mass and high-mass protostars are still unexplained by current gas-grain models. I will then show that gas phase chemistry alone, in which ammonia plays a crucial role, can still produce a large amount of COMs, allowing us to explain their high abundances observed around some of the protostars. Energetic physical processes, such as protostellar luminosity outbursts, can also be important for the production of COMs in large regions of protostellar envelopes.
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