===== On the Detection of Iminopropadienylidene, HNC3, in the ISM =====

K. Kawaguchi, S. Takano, M. Ohishi, S.-I. Ishikawa, K. Miyazawa, N. Kaifu, K. Yamashita, S. Yamamoto, S. Saito, Y. Ohshima, and Y. Endo\\
reported on the\\
**[[https://ui.adsabs.harvard.edu/abs/1992ApJ...396L..49K|Detection of HNCCC in TMC-1]]**\\
//Astrophys. J.// **396**, L49 (1992).\\
The Nobeyama 45 m telescope was used to detect the //J// = 3 – 2, 4 – 3, and 5 – 4 transitions near 28.0, 37.3, and 46.7 GHz. The [[http://www.astro.uni-koeln.de/site/vorhersagen/molecules/ism/HCCNC.html|HCCNC]] isomer was found only slightly earlier, whereas the HC<sub>3</sub>N isomer had been known for a considerable time.\\
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P. D. Gensheimer reported on\\
**[[https://doi.org/10.1023/A:1000744924767|Observations of HCCNC and HNCCC in IRC+10216]]**\\
//Astrophys. Space Sci.// **251**, 199 (1997).\\
The NRAO 12 m telescope was used to detect the //J// = 11 – 10 transition near 102.7 GHz. The HCCNC to HNC<sub>3</sub> ratio is about 8, similar to that in TMC-1. Because of only one detected line, this report should be viewed with some caution.\\
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C. Vastel, K. Kawaguchi, D. Quénard, M. Ohishi, B. Lefloch, R. Bachiller, and H. S. P. Müller\\
used the IRAM 30 m telescope for\\
**[[https://doi.org/10.1093/mnrasl/slx197|High Spectral Resolution Observations of HNC<sub>3</sub> and HCCNC in the L1544 Pre-stellar Core]]**\\
//Mon. Not. R. Astron. Soc.// **474**, L76 (2018).\\
The //J// = 8 – 7, 9 – 8, and 10 – 9 transitions were detected near 74.7, 84.0, and 93.4 GHz. The column density is only slightly smaller than that in TMC-1, similar to HCCNC, even though HC<sub>3</sub>N is less abundant by about one order of magnitide in L1544 compared to TMC-1.\\
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J. Cernicharo, N. Marcelino, M. Agúndez, C. Bermúdez, C. Cabezas, B. Tercero, and J. R. Pardo\\
reported on the\\
**[[https://doi.org/10.1051/0004-6361/202039274|Discovery of HC<sub>4</sub>NC in TMC-1: A study of the isomers of HC<sub>3</sub>N, HC<sub>5</sub>N, and HC<sub>7</sub>N]]**\\
//Astron. Astrophys.// **642**, Art. No. L8 (2020).\\
The authors report the detection of DNC<sub>3</sub>. The observations were obtained with the Yebes 40m radio telescope in the course of a line survey covering 31.0–50.3 GHz.\\
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J. Cernicharo, B. Tercero, C. Cabezas, M. Agúndez, E. Roueff, R. Fuentetaja, N. Marcelino, and P. de Vicente\\
carried out more recently a\\
**[[https://doi.org/10.1051/0004-6361/202348822|Study of the HCCNC and HNCCC isotopologs in TMC-1]]**\\
//Astron. Astrophys.// **682**, Art. No. L13 (2024).\\
They reported in the framework of improved data of the above survey the detection of the three HNC<sub>3</sub> <sup>13</sup>C isotopomers. They determined the <sup>12</sup>C/<sup>13</sup>C ratios of ~90 with scatter that is insignificant with respect to the uncertainties. These values are somewhat lower than ~65 usually found in the the local ISM, but very similar to values of HCCNC <sup>13</sup>C isotopomers and to two of the three HC<sub>3</sub>N <sup>13</sup>C isotopomers. In addition, an H/D ratio of ~53 was reported, similar to the value of 57 ± 2 of HC<sub>3</sub>N.\\
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Contributor(s): H. S. P. Müller; 12, 2017; 11, 2020; 04, 2024

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