First detection of triply-deuterated methanol

B. Parise (1) , Alain Castets (2, 3, 4) , E. Herbst (5) , E. Caux (1) , C. Ceccarelli (6) , I. Mukhopadhyay (7) , A.G.G.M. Tielens (8)

1 CESR - Centre d'étude spatiale des rayonnements
2 L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux
3 OASU - Observatoire aquitain des sciences de l'univers
4 LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac]
5 OSU - Ohio State University [Columbus]
6 LAOG - Laboratoire d'Astrophysique de Grenoble
7 Dakota State University - Dakota State University
8 SRON - SRON Netherlands Institute for Space Research

We report the first detection of triply-deuterated methanol, with 12 observed transitions, towards the low-mass protostar IRAS 16293-2422, as well asmultifrequency observations of 13CH3OH, used to derive the column density of the main isotopomer CH3OH.The derived fractionation ratio [CD3OH]/[CH3OH] averaged on a 10'' beam is 1.4%. Together with previous CH2DOH and CHD2OH observations, the present CD3OH observations are consistent with a formation of methanol on grain surfaces, if the atomic D/H ratio is 0.1 to 0.3 in the accreting gas. Such a high atomic ratio can be reached in the frame of gas-phase chemical models including all deuterated isotopomers of H3+.

Mots clés: Deuterated molecules; protostars; IRAS 16293-2422; methanol; CD3OH

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]

B. Parise, Alain Castets, E. Herbst, E. Caux, C. Ceccarelli, et al.. First detection of triply-deuterated methanol. Astronomy and Astrophysics - A&A, 2004, 416, pp.159-163. ⟨10.1051/0004-6361:20034490⟩. ⟨hal-00000808⟩