G. Esplugues, J. C. Loison, M. Agúndez, G. Molpeceres, N. Marcelino, B. Tercero, and J. Cernicharo
reported on the
Discovery of Linear Propadienone — Study of the Cof linear and Cyclic H2C3O and H2C3S in TMC-1
Astron. Astrophys. 705, Art. No. A206 (2026).
Propadienone was detected in two a-type transitions with K<sub>a/sub> = 0 and J = 4 − 3 and 5 − 4 near 34.6 and 43.2 GHz in the course of a molecular line survey in the 31.0 to 50.3 GHz region carried out with the 40 m Yebes telescope. Assuming a rotational temperature of 4.8 K, taken from the isomeric ortho-cyclopropenone, a cyclopropenone to propadienone ratio of about 9 was derived.