Discovery of linear propadienone: Study of the chemistry of linear and cyclic H$_2$C$_3$O and H$_2$C$_3$S in TMC-1

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Main Authors: Esplugues, G., Loison, J. C., Agúndez, M., Molpeceres, G., Marcelino, N., Tercero, B., Cernicharo, J.
Format: Preprint
Published: 2025
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author Esplugues, G.
Loison, J. C.
Agúndez, M.
Molpeceres, G.
Marcelino, N.
Tercero, B.
Cernicharo, J.
author_facet Esplugues, G.
Loison, J. C.
Agúndez, M.
Molpeceres, G.
Marcelino, N.
Tercero, B.
Cernicharo, J.
contents We report the first detection in space of propadienone, the linear isomer (l-H$_2$C$_3$O) of cyclopropenone (c-H$_2$C$_3$O). We also report the first detection of the isotopologue c-H$_2$$^{13}$CCCO, and c-HDCCCO of c-H$_2$C$_3$O. The astronomical observations are part of QUIJOTE, a line survey of TMC-1 in the frequency range 31.0-50.3 GHz, complemented with data between 71.6-116.0 GHz, and carried out with Yebes-40m and IRAM-30m telescopes, respectively. We obtain a total column density of 3.7$\times$10$^{10}$ cm$^{-2}$ for l-H$_2$C$_3$O at an excitation temperature of 4.8 K. We find that the isomer is about eight times less abundant than the cyclic one. We also report a detailed line-by-line study of cyclopropenethione (c-H$_2$C$_3$S) to compare the abundance of the O and S isomers. We find that cyclic O-isomers are more abundant than cyclic S-isomers; however, the opposite trend is found for the most stable linear isomers, with l-H$_2$C$_3$S being more than one order of magnitude more abundant than l-H$_2$C$_3$O. A comprehensive theoretical chemical analysis shows that the abundances of the H$_2$C$_3$O and H$_2$C$_3$S isomers are controlled by different formation pathways. In particular, while l-H$_2$C$_3$O is potentially produced by dissociative electron recombination reactions, ion-neutral chemistry is more effective at producing l-H$_2$C$_3$S and c-H$_2$C$_3$S.
format Preprint
id arxiv_https___arxiv_org_abs_2511_19775
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Discovery of linear propadienone: Study of the chemistry of linear and cyclic H$_2$C$_3$O and H$_2$C$_3$S in TMC-1
Esplugues, G.
Loison, J. C.
Agúndez, M.
Molpeceres, G.
Marcelino, N.
Tercero, B.
Cernicharo, J.
Astrophysics of Galaxies
We report the first detection in space of propadienone, the linear isomer (l-H$_2$C$_3$O) of cyclopropenone (c-H$_2$C$_3$O). We also report the first detection of the isotopologue c-H$_2$$^{13}$CCCO, and c-HDCCCO of c-H$_2$C$_3$O. The astronomical observations are part of QUIJOTE, a line survey of TMC-1 in the frequency range 31.0-50.3 GHz, complemented with data between 71.6-116.0 GHz, and carried out with Yebes-40m and IRAM-30m telescopes, respectively. We obtain a total column density of 3.7$\times$10$^{10}$ cm$^{-2}$ for l-H$_2$C$_3$O at an excitation temperature of 4.8 K. We find that the isomer is about eight times less abundant than the cyclic one. We also report a detailed line-by-line study of cyclopropenethione (c-H$_2$C$_3$S) to compare the abundance of the O and S isomers. We find that cyclic O-isomers are more abundant than cyclic S-isomers; however, the opposite trend is found for the most stable linear isomers, with l-H$_2$C$_3$S being more than one order of magnitude more abundant than l-H$_2$C$_3$O. A comprehensive theoretical chemical analysis shows that the abundances of the H$_2$C$_3$O and H$_2$C$_3$S isomers are controlled by different formation pathways. In particular, while l-H$_2$C$_3$O is potentially produced by dissociative electron recombination reactions, ion-neutral chemistry is more effective at producing l-H$_2$C$_3$S and c-H$_2$C$_3$S.
title Discovery of linear propadienone: Study of the chemistry of linear and cyclic H$_2$C$_3$O and H$_2$C$_3$S in TMC-1
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2511.19775