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Accueil > Séminaires > Archive des séminaires d’Utinam > 2014

Wolf Dietrich Geppert

Formation of complex molecules and biomolecule precursors in space

mercredi 22 janvier 2014, 10h30

salle de conférences de l’observatoire

Wolf Dietrich Geppert, Centre d’astrobiologie, Université de Stockholm

Résumé :

The possibility of an extraterrestrial origin of biomolecule building blocks has been a subject of intense discussions for many years. The detection of amino acids in meteorites opens the possibility of a delivery of biomolecules synthesized in the interstellar medium or star-forming regions to the primeval Earth. Whereas it can be doubted if more complex species like amino acids and carbohydrates can survive the strong UV radiation in the early Solar System, this does not necessary hold for more primitive precursor molecules like alcohols and nitriles [1]

If these compounds can be synthesised in the interstellar medium, the question of their formation sites and pathway arises. It has been a long-standing issue to what extent comparatively complex carbon-containing interstellar molecules like methanol, ethanol, dimethyl ether and formic acid are produced in the gas-phase or on grain surfaces. We have carried out experimental, computational and observational studies in order to elucidate the origin of these complex organic molecules and the results of these investigations are presented here. Generally, it can be said that there is no universal pathway of forming prebiotic molecules in space, but each species has its own chemical history and must be investigated separately, since even related compounds can have very different generation pathways.

Nitriles, which can serve as amino acid and nucleobase precursors can be synthesized very efficiently in methane-nitrogen dominated atmospheres like the one present on Titan and, possibly, the early ages of Earth. Therefore I will also discuss recent results on the formation and degradation processes of nitriles in Titan’s atmosphere and their possible role in the generation of biomolecules.