Molecular Carbon Chains and Rings in TMC-1

@article{Foss2001MolecularCC,
  title={Molecular Carbon Chains and Rings in TMC-1},
  author={David Foss{\'e} and Jos{\'e} Cernicharo and Maryvonne Gerin and Pierre Cox},
  journal={The Astrophysical Journal},
  year={2001},
  volume={552},
  pages={168 - 174}
}
We present mapping results in several rotational transitions of HC3N, C6H, both cyclic and linear C3H2 and C3H, toward the cyanopolyyne peak of the filamentary dense cloud TMC-1 using the IRAM 30 m and MPIfR 100 m telescopes. The spatial distribution of the cumulene carbon chain propadienylidene H2CCC (hereafter l-C3H2) is found to deviate significantly from the distributions of the cyclic isomer c-C3H2, HC3N, and C6H, which, in turn, look very similar. The cyclic over linear abundance ratio of… 

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References

SHOWING 1-10 OF 22 REFERENCES

Calculations concerning interstellar isomeric abundance ratios for C3H and C3H2.

Calculations of the equilibrium coefficient for the isomerization H2CCCH+ <-> c-C3H3+ as a function of energy shows that equal abundances of these two ions should be produced as relaxation proceeds, in agreement with experimental measurements at high pressure.

Observations of Long CnH Molecules in the Dust Cloud TMC-1

We report detection of the J = 15.5-14.5 and 17.5-16.5 transitions of C8H, a sensitive upper limit for the J=10.5-9.5 transition of C7H, and measurements of two low-frequency transitions of C6H in

The Physics and Chemistry of Small Translucent Molecular Clouds. XIII. The Basic Hydrocarbon Chemistry

We have observed 10 hydrocarbon species at 3 mm wavelength in three translucent clouds and in TMC-1 and L183. The 10 species are C2H, c-C3H, l-C3H, c-C3H2, l-C3H2, CH3CCH, C4H, C4H2, C5H, and C6H,

Astronomical identification of the C3H radical.

A determination of the spectroscopic constraints of C3H that permitted the entire radio spectrum of this molecule to be calculated to high accuracy has been derived from analysis of the combined astronomical and laboratory data presented in the accompanying Letter.

A Study of the Physics and Chemistry of TMC-1

The most striking abundance variations relative to HCO+ along the ridge were seen for HC3N, CH3CCH, and SO, while smaller variations were seen in CS, C2H, and HCN, indicating that the so-called NH3 peak in TMC-1 is probably a peak in the ammonia column density rather than a relative abundance peak.

Neutral-Neutral Reactions in the Interstellar Medium. I. Formation of Carbon Hydride Radicals via Reaction of Carbon Atoms with Unsaturated Hydrocarbons

The reactions of ground-state atomic carbon with acetylene, C2H2 (1), methylacetylene, CH3CCH (2), ethylene, C2H4 (3), and propylene, C3H6 (4), are investigated at relative collision energies between

The hydrocarbon ring C3H2 is ubiquitous in the Galaxy.

A survey of a large number of sources shows that a strong microwave spectral line appears in emission in cold dust clouds, in absorption in the direction of the Galactic center, and exhibits complex profiles toward H II regions.

Spectroscopy of SH (A–X) transition in Ar and Kr matrices: The caging of predissociation

The A(2Σ+)–X(2Π) transition of SH isolated in Ar and Kr matrices is studied by laser induced fluorescence spectroscopy. The (0,0), (1,0), and (2,0) transitions are observed in excitation. These lines

Laboratory and astronomical identification of cyclopropenylidene, C3H2.

Twenty-seven rotational lines of C/sub 3/H/sub 2/ have been identified in the laboratory or in astronomical sources, and the rotational and centrifugal distortion constants of this previously

The Formation of Large Hydrocarbons and Carbon Clusters in Dense Interstellar Clouds

Current gas-phase models of dense cloud chemistry contain molecules through ≈ 10 atoms in size. We have extended two current reaction networks to include unsaturated hydrocarbons and bare carbon