Trapping of noble gases by radiative association with H{sub 3}{sup +} in the protosolar nebula
- UPMC Univ. Paris 06, UMR 7616—CNRS, Laboratoire de Chimie Théorique, F-75005 Paris (France)
- Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne Cedex (France)
The heavy noble gas deficiencies observed in Titan’s atmosphere and in comets have been proposed to be related to a sequestration process by H{sub 3}{sup +} in the gas phase at the early protosolar nebula. Chemical thermodynamics and astrophysics modeling are favorable to this hypothesis, as presented in preceding papers. However, there is a point still to be raised, i.e., that no dynamical study of the efficiency of the collisional processes had been performed so far. Here, we show that, apart from the expected exception of Ne, the rate constants obtained, i.e., 0.7 × 10{sup −18}, 0.5 × 10{sup −16}, and 10{sup −16} (cm{sup 3} s{sup −1}) for Ar, Kr, and Xe, respectively, are reasonably high for such processes, particularly in the case of Kr and Xe. The temperature dependence is also considered, showing a similar behavior for all noble gases with a peak efficiency in the range 50–60 K. Globally, we can conclude that the scenario of sequestration by H{sub 3}{sup +} is definitively comforted by the results of our quantum dynamical treatment. This process may also be responsible of the Ar impoverishment just measured in comet 67P/Churyumov–Gerasimenko by the ROSINA mass spectrometer on board the Rosetta spacecraft.
- OSTI ID:
- 22869093
- Journal Information:
- Astrophysical Journal Letters, Vol. 821, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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