R. Fuentetaja, C. Cabezas, M. Agúndez, B. Tercero, N. Marcelino, J. R. Pardo, P. de Vicente, and J. Cernicharo
reported on the
Discovery of CH₂CCHC₄H and a Rigorous Detection of H₂CCCHC₃N in TMC-1 with the QUIJOTE Line Survey
Astron. Astrophys. 663, Art. No. L3 (2022).
1,2-Heptadiene-4,6-diyne, also known as propadienylbutadiyne or allenyldiacetylene, was detected with the Yebes 40 m radio telescope between 31.2 and 43.0 GHz. 21 lines with 16 ≤ J ≤ 22 and K_a ≤ 2 were identified as being between unblended and not completely blended. T_rot was determined as 9.0 ± 0.5 K. The isoelectronic H₂CCCHC₃N was identified in TMC-1 for the first time through individual lines. The CH₂CCHC₄H to H₂CCCHC₃N ratio was determined as 18 ± 4, somewhat higher than the C₄H to C₃N ratio of ~8. Similarly, the CH₃C₆H to CH₂CCHC₄H ratio is ~0.32, whereas the CH₃C₄H to CH₂CCHC₂H ratio is ~1.1.

Contributor(s): H. S. P. Müller; 07, 2022