===== On the Detection of Butatrienylidene, l-C4H2, in Space =====

Butatrienylidene is a higher energy isomer of diacetylene.\\
J. Cernicharo, C. A. Gottlieb, M Guélin, T. C. Killian, G. Paubert, P. Thaddeus, and J. M. Vrtilek,\\
reported on the\\
**[[https://ui.adsabs.harvard.edu/abs/1991ApJ...368L..43C|Astronomical Detection of H<sub>2</sub>CCCC]]**,\\
//Astrophys. J.// **368**, L43–L45 (1991)\\
The molecule was detectedin the circumstellar envelope of CW Leonis, also known as IRC +10216 using the IRAM 30 m telescope. 10 transitions with 9 ≤ //J'// ≤ 16 were sought, and 8 were detected, two of them partially blended. Six transitions had //K<sub>a</sub>// = 1 (//ortho//) and two had //K<sub>a</sub>// = 0 (//para//).

The Molecule was also deteceted in the dark cloud TMC-1 by\\
K. Kawaguchi, N. Kaifu, M. Ohishi, S.-I. Ishikawa, Y. Hirahara, S. Yamamoto, S. Saito, S. Takano, A. Murakami, J. M. Vrtilek, C. A. Gottlieb, P. Thaddeus, and W. M. Irvine,\\
**[[https://ui.adsabs.harvard.edu/abs/1991PASJ...43..607K|Observations of Cumulene Carbenes, H<sub>2</sub>CCCC and H<sub>2</sub>CCC, in TMC-1]]**,\\
//Publs. Astron. Soc. Japan// **43**, 607–619 (1991)

N. Sakai, T. Sakai, T. Hirota, and S. Yamamoto,\\
reported on\\
**[[https://doi.org/10.1088/0004-637X/702/2/1025|Deuterated Molecules in Warm Carbon Chain Chemsitry: The L1527 Case]]**,\\
//Astrophys. J.// **702**, 1025–1035 (2009)\\
The 5<sub>0,5</sub> – 4<sub>0,4</sub> transition of //l//-C<sub>4</sub>HD near 42.4 GHz was detected with the Nobeyama 45 m telescope in emission.


----

Contributor(s): H. S. P. Müller; 02, 2016

----