C. Cabezas, M. Agúndez, N. Marcelino, B. Tercero, J. R. Pardo, P. de Vicente, and J. Cernicharo
reported on the
Discovery of Interstellar 3-Cyanopropargyl Radical, CH<sub>2</sub>CCCN
Astron. Astrophys. 654, Art. No. L9 (2021).
ortho-CH2C3N was identified through three a-type transitions with J = 8 − 7 to 10 − 9 and Ka = 0 in the course of a molecular line survey of the prototypical cold dark molecular cloud TMC-1 carried out with the Yebes 40 m radio telescope between 31.0 and 50.4 GHz. These transitions displayed partially resolved fine and hyperfine structure splitting; few components were blended by lines of other species. Also observed were four transitions of para-CH2C3N with J = 8 − 7 or 9 − 8 and Ka = 1, which displayed well resolved fine structure splitting; some of these lines were also blended. A value of Trot = 7 ± 1 K was derived. The column density of CH2C3N is about a factor of 100 lower than that of CH2CN. And while CH2C3N is roughly a factor of 10 less abundant than CH3C3N, CH2CN is more abundant than CH3CN by a factor of about 3.
More recently,
C. Cabezas, M. Agúndez, N. Marcelino, C. H. Chang, R. Fuentetaja, B. Tercero, M. Nakajima, Y. Endo, P. de Vicente, and J. Cernicharo
announced the
Identification of the Interstellar 1-Cyanopropargyl Radical (HCCCHCN) in TMC-1
Astron. Astrophys. 693, Art. No. L14 (2025).
Eight a-type transitions with 5 ≤ J ≤ 8 and Ka ≤ 1 were covered with complex fine and hyperfine structure splitting. Many features are close to the noise limit or blended, but sufficiently many features are clear enough and modeled well enough to view the detection as secure. A value of Trot = 7 ± 1 K was derived for this isomer as well. The abundance of 1-cyanopropargyl is slightly higher than that of 3-cyanopropargyl by a factor of about 1.4.
Contributor(s): H. S. P. Müller; 11, 2021; 01, 2025