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Astronomical evolution mechanism of small size polycyclic aromatic hydrocarbon (PAH) was analyzed using the first principles quantum-chemical calculation. Starting model molecule was benzene (C6H6), which would be transformed to (C5H5) due to carbon void created by interstellar high speed proton attack. In a protoplanetary disk around a young star, molecules would be illuminated by high energy photon and ionized to be cationic-(C5H5). Calculation shows that from neutral to tri-cation, molecule keeps original configuration. At a step of sixth cation, there occurs surprising creation of cyclic-C3H2, which is the smallest PAH. Astronomical cyclic-C3H2 had been identified by radio astronomy. Deep photoionization of cyclic-C3H2 brings successive molecular change. Neutral and mono-cation keep cyclic configuration. At a step of di-cation, molecule was transformed to aliphatic chain-C3H2. Finally, chain-C3H2 was decomposed to pure carbon chain-C3 and two hydrogen atoms. Calculated infrared spectrum of those molecules was applied to observed spectrum of Herbig Ae young stars. Observed infrared spectrum could be partially explained by small molecules. Meanwhile, excellent coincidence was obtained by applying a larger molecules as like (C23H12)2+ or (C12H8)2+. Infrared observation is suitable for larger molecules and radio astronomy for smaller asymmetric molecules. It should be noted that these molecules could be identified in a natural way introducing two astronomical phenomena, that is, void-induced molecular deformation and deep photoionization.
Interstellar infrared observation shows featured spectrum due to polycyclic aromatic hydrocarbon (PAH)at wavelength 3.3,6.2,7.6,7.8,8.6,and 11.3 micrometer,which are ubiquitously observed in many astronomical dust clouds and galaxies. Our previous fi
We report the detection of linear and cyclic isomers of C3H and C3H2 towards various starless cores and review the corresponding chemical pathways involving neutral (C3Hx with x=1,2) and ionic (C3Hx+ with x = 1,2,3) isomers. We highlight the role of
We used the Nobeyama 45-m telescope to conduct a spectral line survey in the 3-mm band (85.1-98.4 GHz) toward one of the nearest galaxies with active galactic nucleus NGC 1068 and the prototypical starburst galaxy NGC 253. The beam size of this teles
Astronomical dust molecule of carbon-rich nebula-Lin49 and nebula-Tc1 could be identified to be polycyclic-pure-carbon C23 by the quantum-chemical calculation. Two driving forces were assumed. One is high speed proton attack on coronene-C24H12, which
(Abridged) We have observed velocity resolved spectra of four ro-vibrational far-infrared transitions of C3 between the vibrational ground state and the low-energy nu2 bending mode at frequencies between 1654--1897 GHz using HIFI on board Herschel, i