PhD topic : Laboratory experiments and modeling on the radical-radical and radical-neutral reactivity on the interstellar grains
PhD advisors:
• Patrice Theulé, Aix-Marseille University, Laboratoire d’Astrophysique de Marseille
• Dr Alexei Ivlev Max-Planck-Institut für extraterrestrische Physik, Garching
• François Dulieu Laboratoire d'Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères, Cergy-Pontoise
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Tel: 04 91 05 69 41
PhD topic description:
Interstellar ice is known to be the birthplace of complex organic molecules in dense molecular clouds where stars are forming. We want to investigate what the formation of these molecules tells us about the different steps of a star formation, from the early collapse of the dense core to the formation of the planetary system. At each step of the star formation process the ice mantle covering the interstellar grain is processed (heated, compacted, crystallized, desorbed, reaccreted, amorphized) [Caselli, P., & Ceccarelli 2012]. We want to study the intimate relationship between the star formation processes, the ice mantle, and the several molecules it hosts, to be able to use these molecules as tracers of these processes at the time where radio interferometers such as ALMA and NOEMA provide us more and more high-quality observations of these molecules with an unprecedented spatial resolution.
During the first year, the student will carry laboratory experiments on interstellar ice analogues at Aix-Marseille University and Cergy University. The goal will be to quantify the amount of volatile molecules trapped into water ice and left as a refactory residue on bare grain surface [Collings 2004, Viti 2004], which are observed in cometary ices. The volatiles can be closed shell molecules, or radicals (open shell molecules), or the products of them [Theule, 2013 ].
During the next 18 months, the student will perform experiments on bulk and surface diffusion of molecules at the Max-Planck-Institut für extraterrestrische Physik, Garching on world class state-of-the-art experimental facilities. Diffusion is central in determining the dynamics of the reactions produing the COMs observed by radio astronomy [Minissale 2015, Mispealer 2013].
During the last 6 months, the student will be back at Aix-Marseille University and will implement the results of the experiments in the GRAINOBLE gas-grain code in collaboration with researchers from IPAG,
This PhD is part of and funded by the Astro Chemical Origins European international training network (ACO grant agreement 811312) for 18 months, and by the Max-Planck-Institut für extraterrestrische Physik for the other 18 months. The student will receive a PhD at the Aix-Marseille University (France). The candidate will comply with the European international training network employment rules.
References:
* Our astrochemical heritage, Caselli, P., & Ceccarelli, C. 2012, A&A Rev., 20, 5
* A laboratory survey of the thermal desorption of astrophysically relevant molecules, M. P. Collings, M. A. Anderson, R. Chen, J. W. Dever, S. Viti, D. A. Williams and M. R. S. McCoustra, Mon. Not. R. Astron. Soc. 354, 1133–1140 (2004)
* Evaporation of ices near massive stars: models based on laboratory temperature programmed desorption data, S. Viti, M. P. Collings, J. W. Dever, M. R. S. McCoustra and D. A. Williams
* Thermal reactions in the ice mantle: a step towards molecular complexity in the interstellar medium
Theulé P., Duvernay F., Danger G., Borget F., Bossa J. B., Vinogradoff V., Mispelaer F., Vinogradoff
V., and T. Chiavassa, Advances in Space Research, 52 (4), 2013
* Minissale, M., J.-C. Loison, S. Baouche, H. Chaabouni, E. Congiu, and F. Dulieu. 2015. “Solid-State Formation of CO2 via the H2CO + O Reaction.” Astronomy & Astrophysics 577,
* Diffusion Measurements of CO, HNCO, H 2 CO, and NH 3 in Amorphous Water Ice, Mispelaer, F., P. Theulé, H. Aouididi, J. Noble, F. Duvernay, G. Danger, P. Roubin, O. Morata, T. Hasegawa, and T. Chiavassa. 2013. Astronomy & Astrophysics 555 (June).
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