Abundant Z-cyanomethanimine in the interstellar medium: paving the way to the synthesis of adenine

Rivilla, V.M., Martín-Pintado, J., Jiménez-Serra, I., Zeng, S., Martín, S., Armijos-Abendaño,, J., Requena-Torres, M.A., Aladro, R. and Riquelme, D. 2018. Abundant Z-cyanomethanimine in the interstellar medium: paving the way to the synthesis of adenine. Monthly Notices of the Royal Astronomical Society: Letters 483 (1) , L114-L119. 10.1093/mnrasl/sly228

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Abstract

We report the first detection in the interstellar medium (ISM) of the Z-isomer of cyanomethanimine (HNCHCN), an HCN dimer proposed as precursor of adenine. We identified six transitions of Z-cyanomethanimine, along with five transitions of E-cyanomethanimine, using IRAM 30m observations towards the Galactic Centre quiescent molecular cloud G + 0.693. The Z-isomer has a column density of (2.0 ± 0.6) × 1014 cm−2 and an abundance of 1.5 × 10−9. The relative abundance ratio between the isomers is [Z/E]∼6. This value cannot be explained by the two chemical formation routes previously proposed (gas phase and grain surface), which predicts abundances ratios between 0.9 and 1.5. The observed [Z/E] ratio is in good agreement with thermodynamic equilibrium at the gas kinetic temperature (130−210 K). Since isomerization is not possible in the ISM, the two species may be formed at high temperature. New chemical models, including surface chemistry on dust grains and gas-phase reactions, should be explored to explain our findings. Whatever the formation mechanism, the high abundance of Z-HNCHCN shows that precursors of adenine are efficiently formed in the ISM.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	Oxford University Press
ISSN:	1745-3933
Last Modified:	21 Jun 2023 13:51
URI:	https://orca.cardiff.ac.uk/id/eprint/159166

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