Volume 591, July 2016
|Number of page(s)||4|
|Published online||06 June 2016|
Abundance of HOCO+ and CO2 in the outer layers of the L1544 prestellar core
1 Université de Toulouse, UPS-OMP, IRAP, 31013 Toulouse, France
2 CNRS, IRAP, 9 Av. Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
3 Université de Grenoble Alpes, IPAG, 38000 Grenoble, France
4 CNRS, IPAG, 38000 Grenoble, France
5 Observatorio Astronómico Nacional (OAN, IGN), Calle Alfonso XII, 3, 28014 Madrid, Spain
Received: 3 March 2016
Accepted: 18 May 2016
The L1544 prestellar core has been observed as part of the ASAI IRAM Large Program at 3 mm. These observations led to the detection of many complex molecules. In this Letter, we report the detection of two lines, at 85.5 GHz (40,4–30,3) and 106.9 GHz (50,5–40,4), respectively, of the protonated carbon dioxide ion, HOCO+. We also report the tentative detection of the line at 100.4 GHz (50,5–40,4) of DOCO+. The non-LTE analysis of the detected lines shows that the HOCO+ emission originates in the external layer where non-thermal desorption of other species has previously been observed. Its abundance is (5 ± 2) × 10-11. Modelling of the chemistry involved in the formation and destruction of HOCO+ provides a gaseous CO2 abundance of 2 × 10-7 (with respect to H2) with an upper limit of 2 × 10-6.
Key words: astrochemistry / line: identification / molecular data / radiative transfer
© ESO, 2016
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