2021A&A...649L..15C


Query : 2021A&A...649L..15C

2021A&A...649L..15C - Astronomy and Astrophysics, volume 649, L15-15 (2021/5-1)

Pure hydrocarbon cycles in TMC-1: Discovery of ethynyl cyclopropenylidene, cyclopentadiene, and indene.

CERNICHARO J., AGUNDEZ M., CABEZAS C., TERCERO B., MARCELINO N., PARDO J.R. and DE VICENTE P.

Abstract (from CDS):

We report the detection for the first time in space of three new pure hydrocarbon cycles in TMC-1: c-C3HCCH (ethynyl cyclopropenylidene), c-C5H6 (cyclopentadiene), and c-C9H8 (indene). We derive a column density of 3.1x1011cm–2 for the first cycle and similar values, in the range (1-2)x1013cm–2, for the second and third. This means that cyclopentadiene and indene, in spite of their large size, are exceptionally abundant, only a factor of five less abundant than the ubiquitous cyclic hydrocarbon c-C3H2. The high abundance found for these two hydrocarbon cycles together with the high abundance previously found for the propargyl radical (CH2CCH) and other hydrocarbons, such as vinyl and allenyl acetylene (Agundez et al., 2021A&A...647L..10A; Cernicharo et al., 2021A&A...647L...2C; Cernicharo et al., 2021A&A...647L...3C), start to allow us to quantify the abundant content of hydrocarbon rings in cold dark clouds and to identify the intermediate species that are probably behind the in situ bottom-up synthesis of aromatic cycles in these environments. While c-C3HCCH is most likely formed through the reaction between the radical CCH and c-C3H2, the high observed abundances of cyclopentadiene and indene are difficult to explain through currently proposed chemical mechanisms. Further studies are needed to identify how five- and six-membered rings are formed under the cold conditions of a cloud such as TMC-1.

Abstract Copyright: © ESO 2021

Journal keyword(s): molecular data - line: identification - ISM: molecules - ISM: individual objects: TMC-1 - astrochemistry

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 TMC-1 MoC 04 41 45.9 +25 41 27           ~ 1548 0
2 RAFGL 618 pA* 04 42 53.6242032600 +36 06 53.400902220   16.32   12.59   C-rich 985 0

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2022.10.04-08:47:56

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