Mendoza, E;
Lefloch, B;
Ceccarelli, C;
Kahane, C;
Jaber, AA;
Podio, L;
Benedettini, M;
... Bachiller, R; + view all
(2018)
A search for cyanopolyynes in L1157-B1.
Monthly Notices of the Royal Astronomical Society
, 475
(4)
pp. 5501-5512.
10.1093/mnras/sty180.
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Abstract
We present here a systematic search for cyanopolyynes in the shock region L1157-B1 and its associated protostar L1157-mm in the framework of the Large Program‘Astrochemical Surveys At IRAM’ (ASAI), dedicated to chemical surveys of solar-type star-forming regions with the IRAM 30-m telescope. Observations of the millimeter windows between 72 and 272 GHz permitted the detection of HC3N and its 13C isotopologues, and HC5N (for the first time in a protostellar shock region). In the shock, the analysis of the line profiles shows that the emission arises from the outflow cavities associated with L1157-B1 and L1157-B2. Molecular abundances and excitation conditions were obtained from the analysis of the Spectral Line Energy Distributions under the assumption of Local Thermodynamical Equilibrium or using a radiative transfer code in the Large Velocity Gradient approximation. Towards L1157 mm, the HC3N emission arises from the cold envelope ( Trot=10K Trot=10K ) and a higher-excitation region (Trot = 31K 31K ) of smaller extent around the protostar. We did not find any evidence of 13C or D fractionation enrichment towards L1157-B1. We obtain a relative abundance ratio HC3N/HC5N of 3.3 in the shocked gas. We find an increase by a factor of 30 of the HC3N abundance between the envelope of L1157-mm and the shock region itself. Altogether, these results are consistent with a scenario in which the bulk of HC3N was produced by means of gas phase reactions in the passage of the shock. This scenario is supported by the predictions of a parametric shock code coupled with the chemical model UCL_CHEM.
| Type: | Article |
|---|---|
| Title: | A search for cyanopolyynes in L1157-B1 |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/sty180 |
| Publisher version: | http://doi.org/10.1093/mnras/sty180 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | astrochemistry – stars: formation – ISM: abundances – ISM: jets and outflows – ISM: molecules. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10048137 |
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