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Astrophysics Luncheon Seminar

Roots of Complex Organic Molecules from Star-forming Regions to Comets
Presented by Maria Drozdovskaya
Center for Space and Habitability, University of Bern

Monday, July 23, 2018
12:00 noon in 169-336

Abstract
The chemical evolution of protoplanetary disk materials begins in the earliest prestellar phase of star formation. Under the dark, cold conditions of cores the initial icy mantles of grains are built up. Already at this point, grain-surface chemistry starts to set the composition of these icy layers. Once collapse is initiated, the central protostars can boost chemical processing of the ices by serving as a source of additional UV photons, thereby enhancing photochemistry in both phases, and by heating the dust grains, which allows higher mobility of radicals in the solid phase. Regionally, the heating is sufficient to thermally desorb the ice mantles entirely. In such regions, the chemistry is set via gas-phase reactions. Protoplanetary disks are built up from the collapsing core materials, which are exposed to variable intensities of UV irradiation and heating. The build up of complex organic molecules initiates in the prestellar phase and continues across the subsequent evolutionary stages. I will present the history of the protoplanetary disk composition as unraveled with the help of sophisticated physicochemical models. I will also substantiate the topic by discussing the latest observational constraints. For this purpose, the results from the ALMA-PILS survey on the infant Solar System analogue IRAS16293-2422 will be presented in the context of in situ measurements made by the Rosetta mission on comet 67P/Churyumov-Gerasimenko. Such comparative studies shed light on the earliest physicochemical conditions for our infant Solar System and give hints on the uniqueness of the ingredients to life.

JPL Contact: Neal Turner (3-0049)


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