A rigorous detection of interstellar CH3NCO: An important missing species in astrochemical networks.
The recent analysis of the composition of the frozen surface of comet 67P/Churyumov-Gerasimenko has revealed a significant number of complex organic molecules. Methyl isocyanate (CH3NCO) is one of the more abundant species detected on the comet surface. In this work we report extensive characterization of its rotational spectrum resulting in a list of 1269 confidently assigned laboratory lines and its detection in space towards the Orion clouds where 399 lines of the molecule have been unambiguously identified. We find that the limited mm-wave laboratory data reported prior to our work require some revision. The abundance of CH3NCO in Orion is only a factor of ten below those of HNCO and CH3CN. Unlike the molecular abundances in the coma of comets, which correlate with those of warm molecular clouds, molecular abundances in the gas phase in Orion are only weakly correlated with those measured on the comet surface. We also compare our abundances with those derived recently for this molecule towards Sgr B2 (Halfen et al. 2015). A more accurate abundance of CH3NCO is provided for this cloud based on our extensive laboratory work.
Grupo de Astrofísica Molecular. Instituto de CC. de Materiales de Madrid (ICMM-CSIC). Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain.
J
J
Cernicharo
Laboratory of Mm- and Submm- Spectroscopy. Institute of Physics, Polish Academy of Sciences. Al. Lotnikow 32/46, 02-668 Warszawa, Poland.
Z
Z
Kisiel
Grupo de Astrofísica Molecular. Instituto de CC. de Materiales de Madrid (ICMM-CSIC). Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain.
B
B
Tercero
Grupo de Espectroscopía Molecular (GEM), Edificio Quifima, Área de Química-Física, Laboratorios de Espectroscopía y Bioespectroscopía, Parque Científico UVa, Unidad Asociada CSIC, Universidad de Valladolid, 47011 Valladolid, Spain.
L
L
Kolesniková
Department of Physics, The Ohio State University, 191 W. Woodruff Ave, Columbus, OH 43210, USA; Wright State University, 3640 Colonel Glenn Hwy, Dayton, OH 45435, USA.
I R
IR
Medvedev
Grupo de Astrofísica Molecular. Instituto de CC. de Materiales de Madrid (ICMM-CSIC). Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain.
A
A
López
Department of Physics, The Ohio State University, 191 W. Woodruff Ave, Columbus, OH 43210, USA.
S
S
Fortman
Department of Physics, The Ohio State University, 191 W. Woodruff Ave, Columbus, OH 43210, USA.
M
M
Winnewisser
Department of Physics, The Ohio State University, 191 W. Woodruff Ave, Columbus, OH 43210, USA.
F C
FC
de Lucia
Grupo de Espectroscopía Molecular (GEM), Edificio Quifima, Área de Química-Física, Laboratorios de Espectroscopía y Bioespectroscopía, Parque Científico UVa, Unidad Asociada CSIC, Universidad de Valladolid, 47011 Valladolid, Spain.
J L
JL
Alonso
Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837, 35708 Rennes Cedex 7, France.
J-C
JC
Guillemin
ISM: abundances; ISM: clouds; ISM: individual objects (Orion KL); ISM: molecules; Methods: laboratory: molecular; Molecular data