Inextricable ties between chemical complexity and dynamics of embedded protostellar regions

Seminar Date: 
09 Nov 2016 - 14:00
Maria Drozdovskaya
Centre for Space and Habitability, Bern

Protoplanetary disk midplanes harbor the largest reservoir of icy dust grains that will be incorporated into planetary embryos and comets. The chemical content of these midplane ices originates in the prestellar phase and is shaped during the dynamic transport towards the disk upon the onset of collapse, as shown by means of a sophisticated physicochemical model [Drozdovskaya et al. 2014, 2016a]. In this talk, results for two protoplanetary disks, one grown predominantly via viscous spreading and another via pure infall, will be shown. The models predict that the amount of CO2 can increase during infall via the grain-surface reaction of OH with CO, which is enhanced by photodissociation of H2O ice. Complex organic ices can be produced at abundances as high as a few % of H2O ice at large disc radii (R > 30 AU) at the expense of CH3OH ice. These simulations immediately imply that planet population synthesis models may underestimate the amount of CO2 and overestimate CH3OH ices in planetesimals by disregarding chemical processing between the cloud and disc phases. Links with the unique in situ data on comet 67P/C-G from the Rosetta mission will be addressed. The model results are used to also derive the C/O and C/N ratios as a function of radius in midplanes of embedded disks, which can be used to make links with planet population synthesis studies. During talk the importance of dynamics and chemistry in the embedded phase of star and planet formation for the chemical budget of comets and planetary building blocks will be highlighted.