Show pageOld revisionsBacklinksBack to top This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong. ===== On the Detection of Propadienediylidene, C3, in Space ===== The pure carbon chain molecule propadienediylidene, C<sub>3</sub>, has been detected in the circumstellar envelope of the famous carbon star CW Leo, aka IRC +10216, by\\ K. H. Hinkle, J. J. Keady, and P. F. Bernath,\\ **[[https://doi.org/10.1126/science.241.4871.1319|Detection of C<sub>3</sub> in the Circumstellar Shell of IRC +10216]]**,\\ //Science// **241**, 1319–1322 (1988)\\ at about the same time as the corresponding laboratory spectrum has been recorded. 15 //P// and //R// branch transitions of the ν<sub>3</sub> band were detected around 2040 cm<sup>–1</sup> of which 12 appear to be unblended. Evidence for the presence of C<sub>3</sub> was obtained from the observation of a weak absorption feature at 1968.594 GHz with the KAO toward Sagittarius B2 which was tentatively assigned to //R//(2) of the low-lying ν<sub>2</sub> mode by\\ A. van Orden, J. D. Cruzan, R. A. Provencal, T. F. Giesen, R. J. Saykally, R. T. Boreiko, and A. L. Betz,\\ **[[https://ui.adsabs.harvard.edu/abs/1995ASPC...73...67V|A Search for the C<sub>3</sub> Carbon Cluster in the Interstellar Medium]]**,\\ //ASP Conf. Ser.// **73**, 67–70 (1995)\\ This detection was confirmed by\\ J. Cernicharo, J. R. Goicoechea, and E. Caux,\\ **[[https://doi.org/10.1086/312668|Far-infrared Detection of C<sub>3</sub> in Sagittarius B2 and IRC +10216]]**,\\ //Astrophys. J.// **534**, L199–L202 (2000).\\ The authors identified 9 transitions detected with ISO toward Sgr B2 along with the //R//(2) and //R//(4) toward CW Leo. C<sub>3</sub> has also been observed in the diffuse interstellar medium toward several stars by recording its //A// <sup>1</sup>Π<sub>u</sub> – //X// <sup>1</sup>Σ<sup>+</sup><sub>g</sub>, //v// = 0 – 0 electronic spectrum around 405.2 nm.\\ J. P. Maier, N. M. Lakin, G. A. H. Walker, and D. A. Bohlender,\\ **[[https://doi.org/10.1086/320668|Detection of C<sub>3</sub> in Diffuse Interstellar Clouds]]**,\\ //Astrophys. J.// **553**, 267–273 (2001),\\ studied sightlines toward 20 Aql, ζ Oph, and ζ Per. Two components were detected, a warm one around 60 K and a hot one around 250 K. T. F. Giesen, B. Mookerjea, G. W. Fuchs, A. A. Breier, D. Witsch, R. Simon, and J. Stutzki\\ reported on the\\ **[[https://doi.org/10.1051/0004-6361/201936538|First Detection of the Carbon Chain Molecules <sup>13</sup>CCC and C<sup>13</sup>CC towards SgrB2(M)]]**,\\ //Astron. Astrophys.// **633** Art. No. A120 (2020).\\ The average <sup>12</sup>C/<sup>13</sup>C ratio per C atom is about 20.5, in the expected range. However, C<sup>13</sup>CC is slightly overabundant with a ratio of 14.8 ± 2.7 whereas <sup>13</sup>CCC is underabundant with a ratio of 12.7 ± 2.8; the latter value corresponds to a <sup>12</sup>C/<sup>13</sup>C ratio per C atom of 25.4 ± 5.6 because of two equivalent terminal C atoms.\\ ---- Contributor(s): H. S. P. Müller; 08, 2010; 02, 2020 ---- molecules/ism/c3.txt Last modified: 2020/02/15 14:20by mueller