Cometary ices in forming protoplanetary disc midplanes

摘要: Low-mass protostars are the extrasolar analogues of natal Solar system. Sophisticated physicochemical models used to simulate formation two protoplanetary discs from initial prestellar phase, one dominated by viscous spreading and other pure infall. The results show that volatile fingerprint is modified chemistry en route into disc. This holds relatively independent abundances chemical parameters: physical conditions more important. amount CO2 increases via grain-surface reaction OH with CO, which enhanced photodissociation H2O ice. Complex organic molecules produced during transport through envelope at expense CH3OH Their can be comparable methanol ice (few per cent water ice) large disc radii (R > 30 au). Current Class II may underestimating complex content. Planet population synthesis underestimate overestimate ices in planetesimals disregarding processing between cloud phases. overall C/O C/N ratios differ gas solid little variation beyond inner 10 au both nearly solar case infall, but subsolar when dominates. Chemistry protostellar sets prebiotically significant content icy cometary bodies. Comets thus potentially reflecting provenances midplane nebula.