Speaker
Description
Complex organic molecules are detected in gas and solid phases of astrophysical objects. The origin of these molecules is still debated, but a large part is supposed to form at the surface of astrophysical icy grains. These icy grains that can be observed in dense molecular clouds are processed under high energetic processes (VUV photons, ions, electrons) during the star formation. Processing provides the activation of molecules initially present in these ices allowing the development of an important chemical reactivity. In some environments such as the solar nebula, these grains can be warmed releasing in the gas phase a large part of complex organic molecules initially formed at the surface or in the bulk of ice grains. The non-volatile molecules remain on the grains leading to the formation of refractory organic residues. A part of the processed grains can then accrete leading to the formation of interplanetary objects such as comets and asteroids. Therefore, some of the organic matter present in Solar System objects could originate from ices observed in the interstellar medium.
Based on laboratory experiments, we develop a strategy to investigate the potential correspondence between ices of astrophysical objects and organic molecules observed in the gas and refractory organic residues of these objects. We demonstrate the impact of the initial ice composition on the abundances of molecules observed in the gas phase as well as on the molecular composition of residues remaining after the desorption of the most volatile compounds. These information allow us to draw a first chemical link between ices observed in young stellar objects and the organic matter detected inside meteorites, daughters of interplanetary objects such as asteroids.
In addition, analyses of refractory organic residues show that prebiotic molecules such as amino acids, sugars, nucleobases and peptides are detected, which opens pathways to the development of a prebiotic chemistry on telluric planets from exogenous delivery of organic matter, depending on local environments of these planets.
References:
- The gaseous phase as a probe of the astrophysical solid phase chemistry. N. Abou Mrad, F. Duvernay, R. Isnard, T. Chiavassa and G. Danger. The Astrophysical Journal, 2017, 846, 124
- Photo and thermochemical evolution of astrophysical ice analogs as a source of soluble and insoluble organic materials in Solar System minor bodies. P. de Marcellus, A. Fresneau, R. Brunetto, G. Danger*, F. Duvernay, C. Meinert, U. J. Meierhenrich, F. Borondics, T. Chiavassa, L. Le Sergeant d’Hendecourt. Monthly Notices of the Royal Astronomical Society, 2017, 464, 114-120
- Radical-induced chemistry from VUV photolysis of interstellar ice analogues containing formaldehyde. T. Butscher, F. Duvernay, G. Danger, T. Astronomy and Astrophysique, 2016, 593, A60.
- Insight into the molecular composition of laboratory organic residues produced from interstellar/pre-cometary ice analogues using very high resolution mass spectrometry. G. Danger, A. Fresneau, N. Abou Mrad, P. de Marcellus, F.-R. Orthous-Daunay, F. Duvernay, V. Vuitton, L. Le Sergeant d’Hendecourt, R. Thissen, T. Chiavassa. Geochimica & Cosmochimica Acta, 2016, 189, 184-196.
- Methanol ice VUV photo-processing: GC-MS analysis of volatile organic compounds. N. Abou Mrad, F. Duvernay, T. Chiavassa and G. Danger. Monthly Notices of the Royal Astronomical Society, 2016, 458, 1234-1241.
- Characterization of interstellar/cometary organic residue analogs using very high resolution mass spectrometry, G. Danger, F-R. Orthous-Daunay, P. de Marcellus, P. Modica, V. Vuitton, F. Duvernay, L. Le Sergeant d’Hendecourt, R. Thissen, and T. Chiavassa, Geochimica & Cosmochimica Acta, 2013, 118, 184-201.
Acknowledgments
This work has been funded by the French national programs « Physique Chimie du Milieu Interstellaire » (P.C.M.I, Institut National des Sciences de l’Univers, Centre National de la Recherche Scientifique), the « Programme National de Planétologie » (P.N.P, INSU-CNRS), « Environnements Planetaires et Origines de la Vie » (E.P.O.V, CNRS), the CNES (Centre National d’Etudes Spatiales) from its exobiology program and a PhD grant from the Région Provence Alpes Côte d’Azur (PACA). This work was further supported by the ANR project RAHIIA_SSOM (Grant ANR-16-CE29-0015-01), the ANR project VAHIIA (Grant ANR-12-JS08-0001), the ANR project PeptiSystems (Grant ANR-14-CE33-0020-02) of the French Agence Nationale de la Recherche and finally the Fondation of Aix-Marseille University.
