Universität zu Köln

Margules, L., Belloche, A., Mueller, H. S. P., Motiyenko, R. A., Guillemin, J. -C., Garrod, R. T. and Menten, K. M. (2016). Spectroscopic study and astronomical detection of doubly C-13-substituted ethyl cyanide. Astron. Astrophys., 590. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. We have performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius B2(N) between 84.1 and 114.4 GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. Line intensities of the main isotopic species of ethyl cyanide and its singly C-13-substituted isotopomers observed toward the hot molecular core Sagittarius B2(N2) suggest that the doubly C-13-substituted isotopomers should also be detectable. Aims. We want to determine the spectroscopic parameters of all three doubly C-13-substituted isotopologues of ethyl cyanide to search for them in our ALMA data. Methods. We investigated the laboratory rotational spectra of the three species between 150 GHz and 990 GHz. We searched for emission lines produced by these species in the ALMA spectrum of Sagittarius B2(N2). We modeled their emission and the emission of the C-12 and singly C-13-substituted isotopologues assuming local thermodynamic equilibrium. Results. We identified more than 5000 rotational transitions, pertaining to more than 3500 different transition frequencies, in the laboratory for each of the three doubly C-13-substituted isotopomers. The quantum numbers reach J approximate to 115 and K-a approximate to 35, resulting in accurate spectroscopic parameters and accurate rest frequency calculations beyond 1000 GHz for strong to moderately weak transitions of either isotopomer. All three species are unambiguously detected in our ALMA data. The C-12/C-13 column density ratio of the isotopomers with one C-13 atom to those with two C-13 atoms is about 25. Conclusions. Ethyl cyanide is the second molecule after methyl cyanide for which isotopologues containing two C-13 atoms have been securely detected in the interstellar medium. The model of our ethyl cyanide data suggests that we should be able to detect vibrational satellites of the main species up to at least upsilon(19) = 1 at similar to 1130 K and up to upsilon(13) + upsilon(21) = 2 at similar to 600 K for the isotopologues with one C-13 atom in our present ALMA data. Such satellites may be too weak to be identified unambiguously for isotopologues with two C-13 atoms.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Margules, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Belloche, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mueller, H. S. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Motiyenko, R. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Guillemin, J. -C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Garrod, R. T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Menten, K. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-273349
DOI:	10.1051/0004-6361/201628309
Journal or Publication Title:	Astron. Astrophys.
Volume:	590
Date:	2016
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language COMPLEX ORGANIC-MOLECULES; ROTATIONAL SPECTRUM; INTERSTELLAR-MEDIUM; COLOGNE DATABASE; HOT CORE; SUBMILLIMETER; MILLIMETER; CDMS Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/27334