TY - JOUR

T1 - Rotational spectroscopy of mono-deuterated oxirane (c-C2H3DO) and its detection towards IRAS 16293-2422 B

AU - Mueller, Holger S. P.

AU - Jorgensen, Jes K.

AU - Guillemin, Jean-Claude

AU - Lewen, Frank

AU - Schlemmer, Stephan

PY - 2022/11/15

Y1 - 2022/11/15

N2 - We prepared a sample of mono-deuterated oxirane and studied its rotational spectrum in the laboratory between 490 and 1060 GHz in order to improve its spectroscopic parameters and consequently the calculated rest frequencies of its rotational transitions. The updated rest frequencies were employed to detect c-C2H3DO for the first time in the interstellar medium in the Atacama Large Millimetre/submillimetre Array Protostellar Interferometric Line Survey (PILS) of the Class 0 protostellar system IRAS 16293-2422. Fits of the detected lines using the rotation diagrams yield a temperature of T-rot = 103 +/- 19 K, which in turn agrees well with 125 K derived for the c-C2H4O main isotopologue previously. The c-C2H3DO to c-C2H4O ratio is found to be similar to 0.15 corresponding to a D-to-H ratio of similar to 0.036 per H atom, which is slightly higher than the D-to-H ratio of species such as methanol, formaldehyde, and ketene but lower than those of the larger complex organic species such as ethanol, methyl formate, and glycolaldehyde. This may reflect that oxirane is formed fairly early in the evolution of the prestellar cores. The identification of doubly deuterated oxirane isotopomers in the PILS data may be possibly judged by the amount of mono-deuterated oxirane and the observed trend that multiply deuterated isotopologues have higher deuteration rates than their mono-deuterated variants.

AB - We prepared a sample of mono-deuterated oxirane and studied its rotational spectrum in the laboratory between 490 and 1060 GHz in order to improve its spectroscopic parameters and consequently the calculated rest frequencies of its rotational transitions. The updated rest frequencies were employed to detect c-C2H3DO for the first time in the interstellar medium in the Atacama Large Millimetre/submillimetre Array Protostellar Interferometric Line Survey (PILS) of the Class 0 protostellar system IRAS 16293-2422. Fits of the detected lines using the rotation diagrams yield a temperature of T-rot = 103 +/- 19 K, which in turn agrees well with 125 K derived for the c-C2H4O main isotopologue previously. The c-C2H3DO to c-C2H4O ratio is found to be similar to 0.15 corresponding to a D-to-H ratio of similar to 0.036 per H atom, which is slightly higher than the D-to-H ratio of species such as methanol, formaldehyde, and ketene but lower than those of the larger complex organic species such as ethanol, methyl formate, and glycolaldehyde. This may reflect that oxirane is formed fairly early in the evolution of the prestellar cores. The identification of doubly deuterated oxirane isotopomers in the PILS data may be possibly judged by the amount of mono-deuterated oxirane and the observed trend that multiply deuterated isotopologues have higher deuteration rates than their mono-deuterated variants.

KW - astrochemistry

KW - line: identification

KW - methods: laboratory

KW - ISM: abundances

KW - ISM: individual objects: IRAS 16293-2422

KW - ISM: molecules

KW - ALMA-PILS SURVEY

KW - ETHYLENE-OXIDE

KW - INTERSTELLAR

KW - SPECTRA

KW - PROTOSTELLAR

KW - H2CS

U2 - 10.1093/mnras/stac2525

DO - 10.1093/mnras/stac2525

M3 - Journal article

VL - 518

SP - 185

EP - 193

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

SN - 0035-8711

IS - 1

ER -