===== Reports on the Detection of 1,3-Pentadiyne in the ISM =====

The 1,3-pentadiyne molecule CH<sub>3</sub>C<sub>4</sub>H, aka methyldiacetylene, had been identified in spectra recorded toward TMC-1 by two groups independently and at almost the same time\\
J. M. MacLeod, L. W. Avery, N. W. Broten,\\
**[[https://ui.adsabs.harvard.edu/abs/1984ApJ...282L..89M|The detection of interstellar methyldiacetylene (CH<sub>3</sub>C<sub>4</sub>H)]]**\\
//Astrophys. J.// **282**, L89–L92 (1984);\\
C. M. Walmsley, P. R. Jewell, L. E. Snyder, and G. Winnewisser,\\
**[[https://ui.adsabs.harvard.edu/abs/1984A%26A...134L..11W|Detection of interstellar methyldiacetylene (CH<sub>3</sub>C<sub>4</sub>H) in the dark dust cloud TMC 1]]**\\
//Astron. Astrophys.// **184**, L11–L14 (1984).\\

The molecule was also detected by\\
M. Araki, S. Takano, N. Sakai, S. Yamamoto, T. Oyama, N. Kuze, and K. Tsukiyama,\\
who studied\\
**[[https://doi.org/10.3847/1538-4357/aa8637|Long Carbon Chains in the Warm Carbon-chain-chemistry Source L1527: First Detection of C<sub>7</sub>H in Molecular Clouds]]**,\\
//Astrophys. J.// **847** Art. No. 51 (2017).\\
The three //J// = 11 – 10 transitions with //K// = 0, 1, and 2 were detected near 44.8 GHz with the 100 m GBT.\\

C. Cabezas, R. Fuentetaja, E. Roueff, M. Agúndez, B. Tercero, N. Marcelino, J. R. Pardo, P. de Vicente and J. Cernicharo\\
reported on\\
**[[https://doi.org/10.1051/0004-6361/202142814|New Deuterated Species in TMC-1: Detection of CH<sub>2</sub>DC<sub>4</sub>H with the QUIJOTE line survey]]**,\\
//Astron. Astrophys.// **657** Art. No. L5 (2022).\\
Twelve transition with //J// = 8 to 12 and //K<sub>a</sub>// ≤ 1 were detected with the Yebes 40 m radio telescope. The CH<sub>3</sub>C<sub>4</sub>H to CH<sub>2</sub>DC<sub>4</sub>H abundance ratio of 24 ± 2 is very similar to that of CH<sub>3</sub>C<sub>3</sub>N to CH<sub>2</sub>DC<sub>3</sub>N ratio of 22 ± 2.\\

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Contributor(s): H. S. P. Müller; 7, 2004; 10, 2017; 03, 2022

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