| Issue |
A&A
Volume 687, July 2024
|
|
|---|---|---|
| Article Number | A220 | |
| Number of page(s) | 12 | |
| Section | Interstellar and circumstellar matter | |
| DOI | https://doi.org/10.1051/0004-6361/202449918 | |
| Published online | 16 July 2024 | |
Rotational spectroscopy of CH3OD with a reanalysis of CH3OD toward IRAS 16293–2422*
1
Institute of Radio Astronomy of NASU,
Mystetstv 4,
61002
Kharkiv,
Ukraine
e-mail: ilyushin@rian.kharkov.ua
2
Astrophysik/I. Physikalisches Institut, Universität zu Köln,
Zülpicher Str. 77,
50937
Köln,
Germany
e-mail: hspm@ph1.uni-koeln.de
3
Physikalisch-Meteorologisches Observatorium Davos und Weltstrahlungszentrum (PMOD/WRC),
Dorfstrasse 33,
7260,
Davos Dorf,
Switzerland
4
Niels Bohr Institute, University of Copenhagen,
Øster Voldgade 5–7,
1350
Copenhagen K,
Denmark
5
Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig,
Gaußstr. 17,
38106
Braunschweig,
Germany
6
Univ. Lille, CNRS, UMR 8523 – PhLAM – Physique des Lasers Atomes et Molécules,
59000
Lille,
France
7
Department of Physics, University of New Brunswick,
Saint John,
NB E2L 4L5,
Canada
Received:
9
March
2024
Accepted:
27
May
2024
We have started a measurement campaign of numerous methanol isotopologs in low-lying torsional states in order to provide extensive line lists for radio astronomical observations from an adequate spectroscopic model and to investigate how the intricate vibrationtorsion-rotation interactions manifest themselves in the spectra of different isotopic species. After CD3OH and CD3OD, we turn our focus to CH3OD, which is an important species for studying deuteration in prestellar cores and envelopes that enshroud protostars. Notably, deuteration is frequently viewed as a diagnostic tool for star formation. The measurements used in this study were obtained in two spectroscopic laboratories and cover large fractions of the 34 GHz-1.35 THz range. As done in previous studies, we employed a torsion-rotation Hamiltonian model for our analysis that is based on the rho-axis method. The resulting model describes the ground and first excited torsional states of CH3OD well up to quantum numbers J ⩽ 51 and Ka ⩽ 18. We derived a line list for radio astronomical observations from this model that is accurate up to at least 1.35 THz and should be sufficient for all types of radio astronomical searches for this methanol isotopolog in these two lowest torsional states. This line list was applied to a reinvestigation of CH3OD in data from the Protostellar Interferometric Line Survey of IRAS 16293–2422 obtained with the Atacama Large Millimeter/submillimeter Array. The new accurately determined value for the column density of CH3OD implies that the deuteration in methanol differs in its two functional groups by a factor of ~7.5.
Key words: astrochemistry / molecular data / methods: laboratory: molecular / techniques: spectroscopic / ISM: molecules / ISM: individual objects: IRAS 16293–2422
Electronic supplementary material for this work can be found at https://doi.org/10.5281/zenodo.11460242
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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