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EP: Fachverband Extraterrestrische Physik

EP 15: Planeten und kleine Körper II

EP 15.1: Hauptvortrag

Donnerstag, 15. März 2012, 10:30–11:00, V55.02

Herschel solar system observations: latest results — •Paul Hartogh — Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany

The HssO (Herschel solar system Observations) program aims at determining the distribution, the evolution and the origin of water in Mars, the outer planets, Titan, Enceladus and comets, using the three Herschel instruments HIFI, PACS and SPIRE. It addresses the broad topic of water and its isotopologues in planetary and cometary atmospheres. The nature of cometary activity was investigated by studying water excitation in a sample of comets. The D/H ratio, the key parameter for constraining the origin and evolution of Solar System materials, was determined for the first time in a Jupiter family comet. A comparison with measurements of D/H in Oort cloud comets constrains the composition of pre-solar cometary grains and evolution of the protosolar nebula. New measurements of D/H in giant planets, similarly constraining the composition of proto-planetary ices, will be obtained. The D/H and other isotopic ratios, diagnostics of the evolution of the Mars atmosphere, were accurately measured in H2O and CO. The role of water vapour in the atmospheric chemistry of Mars will be studied by monitoring vertical profiles of H2O and HDO and by searching for several other species. A detailed study of the source of water in the upper atmosphere of the giant planets and Titan is in progress. By monitoring the water abundance and input fluxes in the various objects, and with the help of mapping observations, we will discriminate between the possible sources of water in the outer planets.