Fabien Daniel (IPAG)
Thursday January 21th - 11am
IPAG Seminar Room - IPAG
Isotopes are an invaluable tool to study the history of planetary systems. As an example, the D/H ratios observed in the various bodies of the solar system give insights on the Earth formation scenarios. While the effects responsible of the enrichment/depletion of molecules in a particular isotope are usually identified, it is however often difficult to obtain quantitative contraints and to disentengle the relative contributions of the various processes at work. In particular, the respective role of gas phase chemistry and formation processes on grains are still debated.
In this talk, I will present recent studies performed in the ’Interstellar’ group, that dealt with the deuterated isotopologues of ammonia. I will show how critical the precision of the analysis of the emission of NH2D, ND2H and ND3 isotopologues is in order to obtain clues on the formation process of these isotopologues. Based on new collisional rate coefficients calculated in our group, we built radiative transfer models aimed at reproducing the spectra observed towards two low mass star forming regions, B1b and IRAS 16293E. From the ND2H/NH2D and ND3/ND2H ratios we derived, the formation on grains is favoured with respect to current gas-phase pathways.
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