Abundance of HOCO+ and CO2 in the outer layers of the L1544 prestellar core

Abstract

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 (4,0,4-3,0,3) and 106.9 GHz (5,0,5-4,0,4), respectively, of the protonated carbon dioxide ion, HOCO+. We also report the tentative detection of the line at 100.4 GHz (5,0,5-4,0,4) 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) e-11. Modelling of the chemistry involved in the formation and destruction of HOCO+ provides a gaseous CO2 abundance of 2e-7 (with respect to H2) with an upper limit of 2e-6.

arXiv commentTo appear in A&A Letters

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• Accurate sub-millimetre rest-frequencies for HOCO${}^{+}$ and DOCO${}^{+}$ ions
• Detection of the HC${}_3$NH${}^{+}$ and HCNH${}^{+}$ ions in the L1544 pre-stellar core
• ALCHEMI finds a "shocking" carbon footprint in the starburst galaxy NGC~253
• Protonated CO2 in massive star-forming clumps
• Cyanopolyyne chemistry in the L1544 prestellar core: new insights from GBT observations
• Detection of HOCO+ in the protostar IRAS 16293-2422
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• Chemical exploration of Galactic cold cores
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• Tunneling Enhancement of the Gas-Phase CH + CO2 Reaction at Low Temperature
• Molecular deuterations in massive Starless Clump Candidates
• The emergence of molecular complexity in star forming regions as seen with ASAI
• Carbon chain diversity in L1544 and IRAS 16293-2422: an astrochemical pathfinder study for the SKAO