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SÉMINAIRE DU LERMA
OBSERVATOIRE DE PARIS
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Vendredi 26 janvier 2007 à 14H


77 avenue Denfert Rochereau, Paris 14



Salle de l'Atelier, Observatoire de Paris





Deuteration and Depletion in Cold, Dense ISM



Darek LIS

Caltech



Résumé : In recent years, the chemistry of dense cores has been revisited with the discovery of a plethora of multiply deuterated molecules and of large depletions of CO. It is now firmly established that condensation of stable species onto dust grains leads to systematic molecular differentiation in starless cores. Recent chemical calculations suggest that at high densities a "complete freezeout" occurs and H3+ and its deuterated isotopologues become the only tracers of the molecular gas. As the density threshold for the complete freezeout is time and model dependent, good observational constraints are needed. The submillimeter ground state lines of deuteroammonia provide new opportunities to study the physics and chemistry of cold, dense ISM. Planned absorption studies with the HIFI instrument on Herschel will give insights into the physics and chemistry of foreground clouds on the lines of sight toward bright submillimeter continuum sources, where many complex molecules have already been detected.