Inextricable ties between chemical complexity and dynamics of embedded protostellar regions

  This thesis is centered around the embedded phase of star formation and the chemical links between the various stages of evolution. The primary goal of this work is to pinpoint the origins of cometary complex organic molecules in the preceding protoplanetary disk and prestellar stages, both in the gas and solid phases. The grand motivation is to identify our interstellar roots. This work is unique in comparison to earlier publications due to the dynamic nature of the models used in combination with the large comprehensive chemical network. Three chapters in this book pertain to physicochemical models and an additional one is of observational nature. Altogether, this thesis is an attempt to piece together the chemical connection between the prestellar core, the protoplanetary disk and the protoplanetary and cometary materials. The main take-home message is that the seeding of infant Solar System building blocks with complex organic molecules is unavoidable as a result of chemistry during protoplanetary disk assembly.  Laboratory astrophysics and astrochemistr

The chemical connection between 67P/C-G and IRAS 16293-2422

Interstellar matter and star formatio

Tracing the cold and warm physico-chemical structure of deeply embedded protostars: IRAS 16293-2422 vs. VLA 1623-2417

Stars and planetary system

Prestellar grain-surface origins of deuterated methanol in comet 67P/Churyumov-Gerasimenko

Stars and planetary system

The edge-on protoplanetary disk HH 48 NE: II. Modeling ices and silicates

Stars and planetary system

Protostellar and cometary detections of organohalogens

Organohalogens, a class of molecules that contain at least one halogen atom bonded to carbon, are abundant on the Earth where they are mainly produced through industrial and biological processes1. Consequently, they have been proposed as biomarkers in the search for life on exoplanets2. Simple halogen hydrides have been detected in interstellar sources and in comets, but the presence and possible incorporation of more complex halogen-containing molecules such as organohalogens into planet-forming regions is uncertain3,4. Here we report the interstellar detection of two isotopologues of the organohalogen CH3Cl and put some constraints on CH3F in the gas surrounding the low-mass protostar IRAS 16293–2422, using the Atacama Large Millimeter/submillimeter Array (ALMA). We also find CH3Cl in the coma of comet 67P/Churyumov–Gerasimenko (67P/C-G) by using the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument. The detections reveal an efficient pre-planetary formation pathway of organohalogens. Cometary impacts may deliver these species to young planets and should thus be included as a potential abiotical production source when interpreting future organohalogen detections in atmospheres of rocky planets.Stars and planetary systemsInterstellar matter and star formatio

On the origin and evolution of the material in 67P/Churyumov-Gerasimenko

International audiencePrimitive objects like comets hold important information on the material that formed our solar system. Several comets have been visited by spacecraft and many more have been observed through Earth- and space-based telescopes. Still our understanding remains limited. Molecular abundances in comets have been shown to be similar to interstellar ices and thus indicate that common processes and conditions were involved in their formation. The samples returned by the Stardust mission to comet Wild 2 showed that the bulk refractory material was processed by high temperatures in the vicinity of the early sun. The recent Rosetta mission acquired a wealth of new data on the composition of comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) and complemented earlier observations of other comets. The isotopic, elemental, and molecular abundances of the volatile, semi-volatile, and refractory phases brought many new insights into the origin and processing of the incorporated material. The emerging picture after Rosetta is that at least part of the volatile material was formed before the solar system and that cometary nuclei agglomerated over a wide range of heliocentric distances, different from where they are found today. Deviations from bulk solar system abundances indicate that the material was not fully homogenized at the location of comet formation, despite the radial mixing implied by the Stardust results. Post-formation evolution of the material might play an important role, which further complicates the picture. This paper discusses these major findings of the Rosetta mission with respect to the origin of the material and puts them in the context of what we know from other comets and solar system objects

Inextricable ties between chemical complexity and dynamics of embedded protostellar regions

  This thesis is centered around the embedded phase of star formation and the chemical links between the various stages of evolution. The primary goal of this work is to pinpoint the origins of cometary complex organic molecules in the preceding protoplanetary disk and prestellar stages, both in the gas and solid phases. The grand motivation is to identify our interstellar roots. This work is unique in comparison to earlier publications due to the dynamic nature of the models used in combination with the large comprehensive chemical network. Three chapters in this book pertain to physicochemical models and an additional one is of observational nature. Altogether, this thesis is an attempt to piece together the chemical connection between the prestellar core, the protoplanetary disk and the protoplanetary and cometary materials. The main take-home message is that the seeding of infant Solar System building blocks with complex organic molecules is unavoidable as a result of chemistry during protoplanetary disk assembly.  </div

Midplane Ices in the Embedded Phase

Interstellar matter and star formatio