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arXiv · 2302.08825

Discovery of CH3CHCO in TMC-1 with the QUIJOTE line survey

R. Fuentetaja·C . Bermúdez·C. Cabezas·M. Agúndez·B. Tercero·N. Marcelino·J. R. Pardo·L. Margulès·R. A. Motiyenko·J. -C. Guillemin·P. de Vicente·J. Cernicharo
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Abstract

We report the detection of methyl ketene towards TMC-1 with the QUIJOTE line survey. Nineteen rotational transitions with rotational quantum numbers ranging from J = 3 up to J = 5 and Ka =< 2 were identified in the frequency range 32.0-50.4 GHz, 11 of which arise above the 3{\sigma} level. We derived a column density for CH3CHCO of N=1.5x10^11 cm-2 and a rotational temperature of 9 K. Hence, the abundance ratio between ketene and methyl ketene, CH2CO/CH3CHCO, is 93. This species is the second C3H4O isomer detected. The other, trans-propenal (CH2CHCHO), corresponds to the most stable isomer and has a column density of N=(2.2+-0.3)x10^11 cm-2, which results in an abundance ratio CH2CHCHO/CH3CHCO of 1.5. The next non-detected isomer with the lowest energy is cis-propenal, which is therefore a good candidate for future discovery. We have carried out an in-depth study of the possible gas-phase chemical reactions involving methyl ketene to explain the abundance detected, achieving good agreement between chemical models and observations.

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R. Fuentetaja, C . Bermúdez, C. Cabezas, M. Agúndez, B. Tercero, N. Marcelino, J. R. Pardo, L. Margulès, R. A. Motiyenko, J. -C. Guillemin, P. de Vicente, J. Cernicharo. 2023-02-17. Discovery of CH3CHCO in TMC-1 with the QUIJOTE line survey. https://doi.org/10.1051/0004-6361%2F202245732

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