The millimeter-wave spectrum of methyl ketene and the astronomical search for it★
1 Université de Lille, Faculté des Sciences et Technologies, Département Physique, Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, 59655 Villeneuve d’Ascq Cedex, France
2 Observatorio Astronómico Nacional (IGN), C/Alfonso XII 3, 28014 Madrid, Spain
3 Instituto de Física Fundamental, Dpt. of Molecular Astrophysics, CSIC, C/ Serrano 121, 28006 Madrid, Spain
4 Sorbonne Université, CNRS, Laboratoire de Chimie Théorique, LCT, 75005 Paris, France
5 Univ. Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR – UMR6226, 35000 Rennes, France
Accepted: 11 July 2018
Context. The analysis of isomeric species of a compound observed in the interstellar medium (ISM) is a useful tool to understand the chemistry of complex organic molecules. It could, likewise, assist in the detection of new species.
Aims. Our goal consists in analyzing one of the two most stable species of the C3H4O family, methyl ketene, whose actual rotational parameters are not precise enough to allow its detection in the ISM. The obtained parameters will be used to search for it in the high-mass star-forming regions Orion KL and Sagittarius B2, as well as in the cold dark clouds TMC-1 in the Taurus Molecular Cloud and Barnard 1 (B1–b).
Methods. A millimeter-wave room-temperature rotational spectrum of methyl ketene was recorded from 50 to 330 GHz. The internal rotation analysis of its ground state and first torsional excited state was performed with the rho-axis method employing the RAM36 program.
Results. More than 3000 transitions of the rotational spectrum of the ground state (Kamax = 18) and first torsional excited state (Kamax = 13) of methyl ketene were fitted using a Hamiltonian that contains 41 parameters with a root mean square of 44 kHz. Column density limits were calculated but no lines were detected in the ISM belonging to methyl ketene.
Key words: ISM: molecules / methods: laboratory: molecular / submillimeter: ISM / molecular data / line: identification
Full Tables 2 and 3 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/619/A92
© ESO 2018
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.