Rotational excitation of mono- and doubly-deuterated water by hydrogen molecules

A. Faure (1) , Laurent Wiesenfeld (1) , Yohann Scribano (2) , C. Ceccarelli (1)

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
2 ICB - Laboratoire Interdisciplinaire Carnot de Bourgogne

Rate coefficients for rotational transitions in HDO and D2O induced by H-2 collisions below 300 K are presented. Calculations have been performed at the close-coupling and coupled-states levels with the deuterated variants of the H2O-H-2 interaction potential of Valiron et al. The HDO-H-2 and D2O-H-2 rate coefficients are compared to the corresponding rate coefficients for HDO-He and H2O-H-2, respectively. Significant differences are observed. In particular the new HDO rate coefficients are found to be significantly larger (by up to three orders of magnitude) than the corresponding HDO-He rate coefficients. The impact of the new HDO rate coefficients is examined with the help of non-LTE radiative transfer calculations. A number of potential HDO maser lines are finally identified, in particular the 80.6 GHz (1(1,0)-1(1,1)) transition.

Mots clés: INTERSTELLAR HEAVY-WATER; HERSCHEL OBSERVATIONS; SPECTRAL SURVEYS; HDO; TEMPERATURE; ENERGY; H2O; H-2

Domaines: Planète et Univers [physics]

A. Faure, Laurent Wiesenfeld, Yohann Scribano, C. Ceccarelli. Rotational excitation of mono- and doubly-deuterated water by hydrogen molecules. Monthly Notices of the Royal Astronomical Society, 2012, 420, pp.699--704. ⟨10.1111/j.1365-2966.2011.20081.x⟩. ⟨hal-00760253⟩