Radiative association and the synthesis of long carbon chain molecules in interstellar clouds

1983 ◽  
Vol 267 ◽  
pp. L121 ◽  
Author(s):  
D. R. Bates
Keyword(s):  
Carbon Chain ◽  
Interstellar Clouds ◽  
Chain Molecules ◽  
Radiative Association

Carbon chain molecules in interstellar clouds

1979 ◽  
Vol 65 (1) ◽  
pp. 83-93 ◽  
Author(s):  
G. Winnewisser ◽  
C. M. Walmsley
Keyword(s):  
Carbon Chain ◽  
Interstellar Clouds ◽  
Chain Molecules

Sulfur-bearing carbon chain molecules in interstellar clouds

1988 ◽  
Vol 31 ◽  
pp. 459-462 ◽  
Author(s):  
Hiroko Suzuki ◽  
Masatoshi Ohishi ◽  
Norio Kaifu ◽  
Takashi Kasuga ◽  
Shin-ichi Ishikawa ◽  
...  
Keyword(s):  
Carbon Chain ◽  
Interstellar Clouds ◽  
Chain Molecules

scholarly journals Activity of the first interstellar comet 2I/Borisov around perihelion: results from Indian observatories

2021 ◽  
Vol 502 (3) ◽  
pp. 3491-3499
Author(s):  
K Aravind ◽  
Shashikiran Ganesh ◽  
Kumar Venkataramani ◽  
Devendra Sahu ◽  
Dorje Angchuk ◽  
...  
Keyword(s):  
Solar System ◽  
Production Rate ◽  
Rate Ratio ◽  
Carbon Chain ◽  
Astronomical Observatory ◽  
Nucleus Size ◽  
Chain Molecules ◽  
Molecular Emission ◽  
Imaging And Spectroscopy ◽  
Gas Ratio

ABSTRACT Comet 2I/Borisov is the first true interstellar comet discovered. Here, we present results from observational programs at two Indian observatories, 2 m Himalayan Chandra Telescope at the Indian Astronomical Observatory, Hanle (HCT) and 1.2 m telescope at the Mount Abu Infrared Observatory (MIRO). Two epochs of imaging and spectroscopy were carried out at the HCT and three epochs of imaging at MIRO. We found CN to be the dominant molecular emission on both epochs, 2019 November 30 and December 22, at distances of rH = 2.013 and 2.031 au, respectively. The comet was inferred to be relatively depleted in Carbon bearing molecules on the basis of low C2 and C3 abundances. We find the production rate ratio, Q(C2)/Q(CN) = 0.54 ± 0.18, pre-perihelion and Q(C2)/Q(CN) = 0.34 ± 0.12 post-perihelion. This classifies the comet as being moderately depleted in carbon chain molecules. Using the results from spectroscopic observations, we believe the comet to have a chemically heterogeneous surface having variation in abundance of carbon chain molecules. From imaging observations, we infer a dust-to-gas ratio similar to carbon chain depleted comets of the Solar system. We also compute the nucleus size to be in the range 0.18 km ≤ r ≤ 3.1 km. Our observations show that 2I/Borisov’s behaviour is analogous to that of the Solar system comets.

scholarly journals Carbon-chain molecules in molecular outflows and Lupus I region – new producing region and new forming mechanism

2019 ◽  
Vol 488 (1) ◽  
pp. 495-511
Author(s):  
Yuefang Wu ◽  
Xunchuan Liu ◽  
Xi Chen ◽  
Lianghao Lin ◽  
Jinghua Yuan ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Molecular Cloud ◽  
Carbon Chain ◽  
Species Range ◽  
Chain Molecules ◽  
Forming Mechanism ◽  
Molecular Outflows ◽  
Chemical Models ◽  
Cloud Complex

Abstract Using the new equipment of the Shanghai Tian Ma Radio Telescope, we have searched for carbon-chain molecules (CCMs) towards five outflow sources and six Lupus I starless dust cores, including one region known to be characterized by warm carbon-chain chemistry (WCCC), Lupus I-1 (IRAS 15398-3359), and one TMC-1 like cloud, Lupus I-6 (Lupus-1A). Lines of HC3N J = 2 − 1, HC5N J = 6 − 5, HC7N J = 14 − 13, 15 − 14, 16 − 15, and C3S J = 3 − 2 were detected in all the targets except in the outflow source L1660 and the starless dust core Lupus I-3/4. The column densities of nitrogen-bearing species range from 1012 to 1014 cm−2 and those of C3S are about 1012 cm−2. Two outflow sources, I20582+7724 and L1221, could be identified as new carbon-chain-producing regions. Four of the Lupus I dust cores are newly identified as early quiescent and dark carbon-chain-producing regions similar to Lup I-6, which together with the WCCC source, Lup I-1, indicate that carbon-chain-producing regions are popular in Lupus I which can be regard as a Taurus-like molecular cloud complex in our Galaxy. The column densities of C3S are larger than those of HC7N in the three outflow sources I20582, L1221, and L1251A. Shocked carbon-chain chemistry is proposed to explain the abnormal high abundances of C3S compared with those of nitrogen-bearing CCMs. Gas-grain chemical models support the idea that shocks can fuel the environment of those sources with enough S+ thus driving the generation of S-bearing CCMs.

Ion-molecule reactions with carbon chain molecules: reactions with diacetylene and the diacetylene cation

1986 ◽  
Vol 64 (4) ◽  
pp. 641-648 ◽  
Author(s):  
Seksan Dheandhanoo ◽  
Leonard Forte ◽  
Arnold Fox ◽  
Diethard K. Bohme
Keyword(s):  
Carbon Chain ◽  
Heat Of Formation ◽  
Buffer Gas ◽  
Proton Affinities ◽  
Chain Molecules ◽  
Ion Flow ◽  
Molecule Reaction ◽  
Ion Molecule Reactions ◽  
A Value ◽  
Selected Ion Flow Tube

Reactions of hydrocarbon and carbon/nitrogen ions with diacetylene and of the diacetylene radical cation with various molecules have been examined with a view to molecular growth by ion–molecule reaction. Measurements were performed with a Selected-Ion Flow Tube (SIFT) apparatus at 296 ± 2 K of the rate constants and product distributions for the reactions of C+, CH3+, C2H2+, C3H+, CN+, C2N+, and C2N2+ with C4H2 and of C4H2+ with H2, CO, C2H2, C2N2, and C4H2. Condensation and association reactions which build up the carbon content of the ion were observed to compete with charge transfer. For the reactions of CN+ and C2N2+ with C4H2 this growth involved the addition of cyanide to the carbon chain. The kinetics of protonation of diacetylene were also investigated. It was possible to bracket the proton affinity of diacetylene between the known proton affinities of HCN and CH3OH with a value for PA(C4H2) = 177 ± 5 kcal mol−1, which results in a heat of formation for C4H3+ of 305 ± 5 kcal mol−1. Numerous secondary association reactions were observed to form adduct ions in helium buffer gas at total pressures of a few tenths of a Torr with rates near the collision rate. This was the case for C6H4+ (C4H2+•C2H2), C7H5+ (C3H3+•C4H2), C8H4+ (C4H2+•C4H2), C8H5+ (C4H3+•C4H2), C9H3+ (C5H+•C4H2), C9H4+ (C5H2+•C4H2), C9H5 (C5H3+•C4H2), C10H4+ (C6H2+•C4H2), C10H5+ (C6H3+•C4H2), C11H7+ (C3H3+•(C4H2)2), C12H6+ (C4H2+•(C4H2)2), C9H3N+ (HC5N+•C4H2), and C10H4N+ (C2N+•(C4H2)2) where the reactants are indicated in parentheses. The observed high rates of association imply the formation of chemical bonds in the adduct ions but the structures of these ions were not resolved experimentally. In most instances there seems little basis for preferring acyclic over cyclic adduct ions.

Long Carbon Chain Molecules in the Laboratory and in Space

1980 ◽  
pp. 59-65 ◽  
Author(s):  
G. Winnewisser ◽  
F. Toelle ◽  
H. Ungerechts ◽  
C. M. Walmsley
Keyword(s):  
Carbon Chain ◽  
Chain Molecules

Mapping observations of sulfur-containing carbon-chain molecules in Taurus Molecular Cloud 1 (TMC-1)

1992 ◽  
Vol 394 ◽  
pp. 539 ◽  
Author(s):  
Yasuhiro Hirahara ◽  
Hiroko Suzuki ◽  
Satoshi Yamamoto ◽  
Kentarou Kawaguchi ◽  
Norio Kaifu ◽  
...  
Keyword(s):  
Molecular Cloud ◽  
Carbon Chain ◽  
Chain Molecules ◽  
Sulfur Containing ◽  
Taurus Molecular Cloud

scholarly journals Long Carbon Chain Molecules in the Laboratory and in Space

1980 ◽  
Vol 87 ◽  
pp. 59-65 ◽  
Author(s):  
G. Winnewisser ◽  
F. Toelle ◽  
H. Ungerechts ◽  
C. M. Walmsley
Keyword(s):  
Radio Frequency ◽  
Hydrogen Cyanide ◽  
Carbon Chain ◽  
Remarkable Property ◽  
Chain Molecules ◽  
Temperature Changes ◽  
Hydrogen Addition ◽  
Heavy Atoms ◽  
Hydrogen Isocyanide ◽  
Radio Frequency Discharge

The unsaturated long carbon chain molecules of the type HC2n+1N (with n=1,2..) have the remarkable property of being very stable under a wide variety of different laboratory and interstellar conditions. In fact, they can be synthesized in the laboratory under the action of a radio frequency discharge in a mixture of acetylene, HCCH, and hydrogen cyanide, HCN (Creswell et al. 1977, Winnewisser et al. 1978). Once they are formed they are for example very stable towards temperature changes as well as saturation of the carbon bonds due to hydrogen addition. In the laboratory their chief cause of destruction is polymerization. These experiments were triggered by our observation that in the course of producing hydrogen isocyanide, HNC, (Creswell et al. 1976) by reacting CH3I with N2in a gas discharge, also small amounts of HC3N were present which clearly requires the joining together of four heavy atoms from different starting molecules.

scholarly journals Laboratory and Modeling Studies of Chemistry in Dense Molecular Clouds

1980 ◽  
Vol 87 ◽  
pp. 331-336
Author(s):  
W.T. Huntress ◽  
S. S. Prasad ◽  
G. F. Mitchell
Keyword(s):  
Chemical Equilibrium ◽  
Molecular Clouds ◽  
Evolutionary Model ◽  
Chemical Processes ◽  
Chemical Library ◽  
Interstellar Clouds ◽  
Organic Species ◽  
Radiative Association ◽  
Simple Chemical ◽  
Complex Organic

A chemical evolutionary model with a large number of species and a large chemical library is used to examine the principal chemical processes in interstellar clouds. Simple chemical equilibrium arguments show the potential for synthesis of very complex organic species by ion-molecule radiative association reactions.

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