Photochemical Enrichment of Deuterium in Titan's Atmosphere: new lights from Cassini-Huygens

Audrey Moudens (1) , Daniel Cordier (1, 2) , Olivier Mousis (3) , J. Lunine (4) , Véronique Vuitton (4, 5)

1 IPR - Institut de Physique de Rennes
2 ENSCR - Ecole Nationale Supérieure de Chimie de Rennes
3 UTINAM - Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213)
4 LPL - Lunar and Planetary Laboratory [Tucson]
5 LPG - Laboratoire de Planétologie de Grenoble

We reinvestigate a scenario initially proposed by Pinto et al. (1986) and Lunine et al. (1999), dealing with the photochemical enrichment of deuterium in the atmosphere of Titan, which is based on the possibility that the initial methane reservoir accessible to the atmosphere was larger than what is seen today, in light of the recent Cassini-Huygens measurements (Bézard et al. 2007). We show that this photochemical mechanism is not efficient enough in the atmosphere of Titan to explain its current D/H value, even if the current atmospheric reservoir of CH_4 is postulated to exist since 4.5 Gyr.

Audrey Moudens, Daniel Cordier, Olivier Mousis, J. Lunine, Véronique Vuitton. Photochemical Enrichment of Deuterium in Titan's Atmosphere: new lights from Cassini-Huygens. SF2A-2008 : Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics, Jul 2008, Paris, France. pp.427. ⟨insu-00361726⟩