The ALMA-PILS survey: the first detection of doubly deuterated methyl formate (CHD₂OCHO) in the ISM

Manigand, S.; Calcutt, H.; Jørgensen, J. K.; Taquet, V.; Müller, H. S. P.; Coutens, A.; Wampfler, S. F.; Ligterink, N. F. W.; Drozdovskaya, M. N.; Kristensen, L. E.; van der Wiel, M. H. D.; Bourke, T. L. (2019). The ALMA-PILS survey: the first detection of doubly deuterated methyl formate (CHD₂OCHO) in the ISM. Astronomy and astrophysics, 623(A69), A69. EDP Sciences 10.1051/0004-6361/201832844

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Studies of deuterated isotopologues of complex organic molecules can provide important constraints on their origin in regions of star formation. In particular, the abundances of deuterated species are very sensitive to the physical conditions in the environment where they form. Due to the low temperatures in regions of star formation, these isotopologues are enhanced to significant levels, making detections of multiply-deuterated species possible. However, for complex organic species, only the multiply-deuterated variants of methanol and methyl cyanide have been reported so far. The aim of this paper is to initiate the characterisation of multiply-deuterated variants of complex organic species with the first detection of doubly-deuterated methyl formate, CHD₂OCHO. We use ALMA observations from the Protostellar Interferometric Line Survey (PILS) of the protostellar binary IRAS 16293-2422, in the spectral range of 329.1 GHz to 362.9 GHz. We report the first detection of doubly-deuterated methyl formate CHD₂OCHO in the ISM. The D/H ratio of CHD₂OCHO is found to be 2-3 times higher than the D/H ratio of CH₂DOCHO for both sources, similar to the results for formaldehyde from the same dataset. The observations are compared to a gas-grain chemical network coupled to a dynamical physical model, tracing the evolution of a molecular cloud until the end of the Class 0 protostellar stage. The overall D/H ratio enhancements found in the observations are of the same order of magnitude as the predictions from the model for the early stages of Class 0 protostars. However, the higher D/H ratio of CHD₂OCHO compared to the D/H ratio of CH2₂DOCHO is still not predicted by the model. This suggests that a mechanism is enhancing the D/H ratio of singly- and doubly-deuterated methyl formate that is not in the model, e.g. mechanisms for H-D substitutions.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Center for Space and Habitability (CSH)
08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute
08 Faculty of Science > Physics Institute > NCCR PlanetS

UniBE Contributor:

Wampfler, Susanne; Ligterink, Niels Frank Willem and Drozdovskaya, Maria Nikolayevna

Subjects:

500 Science > 520 Astronomy
500 Science
500 Science > 530 Physics

ISSN:

0004-6361

Publisher:

EDP Sciences

Language:

English

Submitter:

Danielle Zemp

Date Deposited:

14 Apr 2020 14:03

Last Modified:

19 Apr 2020 02:53

Publisher DOI:

10.1051/0004-6361/201832844

ArXiv ID:

1811.09102v1

BORIS DOI:

10.7892/boris.142649

URI:

https://boris.unibe.ch/id/eprint/142649

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