Astrochemistry at work in the L1157-B1 shock: acetaldehyde formation
Date Issued
2015
Author(s)
•
•
Ceccarelli, C.
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•
Viti, S.
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Bachiller, R.
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Lefloch, B.
Description
The authors are grateful to P. Caselli for instructive comments and suggestions, as well as to the IRAM staff for its help in the calibration of the PdBI data. This research has received funding from the European Commission Seventh Framework Programme (FP/2007-2013, no. 283393, RadioNet3), the PRIN INAF 2012 – JEDI and the Italian Ministero dell'Istruzione, Università e Ricerca through the grant Progetti Premiali 2012 – iALMA. LP has received funding from the European Union Seventh Framework Programme (FP7/2007-2013, n. 267251). CC and BL acknowledge the financial support from the French Space Agency CNES, and RB from Spanish MINECO (FIS2012-32096).
Abstract
The formation of complex organic molecules (COMs) in protostellar environments is a hotly debated topic. In particular, the relative importance of the gas phase processes as compared to a direct formation of COMs on the dust grain surfaces is so far unknown. We report here the first high-resolution images of acetaldehyde (CH3CHO) emission towards the chemically rich protostellar shock L1157-B1, obtained at 2 mm with the IRAM Plateau de Bure interferometer. Six blueshifted CH3CHO lines with Eu = 26-35 K have been detected. The acetaldehyde spatial distribution follows the young (̃ 2000 yr) outflow cavity produced by the impact of the jet with the ambient medium, indicating that this COM is closely associated with the region enriched by iced species evaporated from dust mantles and released into the gas phase. A high CH3CHO relative abundance, 2-3 × 10-8, is inferred, similarly to what found in hot corinos. Astrochemical modelling indicates that gas phase reactions can produce the observed quantity of acetaldehyde only if a large fraction of carbon, of the order of 0.1 per cent, is locked into iced hydrocarbons.
Volume
449
Start page
L11
Issn Identifier
0035-8711
Ads BibCode
2015MNRAS.449L..11C
Rights
open.access
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