The interstellar chemistry of C3H and C3H2 isomers

Abstract

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 the branching ratio of electronic Dissociative Recombination (DR) reactions of C3H2+ and C3H3+ isomers showing that the statistical treatment of the relaxation of C3H* and C3H2* produced in these DR reactions may explain the relative c,l-C3H and c,l-C3H2 abundances. We have also introduced in the model the third isomer of C3H2 (HCCCH). The observed cyclic-to-linear C3H2 ratio vary from 110 + or - 30 for molecular clouds with a total density around 1e4 molecules.cm-3 to 30 + or - 10 for molecular clouds with a total density around 4e5 molecules.cm-3, a trend well reproduced with our updated model. The higher ratio for low molecular cloud densities is mainly determined by the importance of the H + l-C3H2 -> H + c-C3H2 and H + t-C3H2 -> H + c-C3H2 isomerization reactions.

Accepted for publication in MNRAS

References in corpus (13)

• Non-thermal desorption from interstellar dust grains via exothermic surface reactions
• The 2014 KIDA network for interstellar chemistry
• Binding energies: new values and impact on the efficiency of chemical desorption
• Modeling Complex Organic Molecules in dense regions: Eley-Rideal and complex induced reaction
• The effect of uncertainties on chemical models of dark clouds
• Discovery of Fulminic Acid, HCNO, in Dark Clouds
• The interstellar gas-phase chemistry of HCN and HNC
• Discovery of interstellar ketenyl (HCCO), a surprisingly abundant radical
• Investigating the Minimum Energy Principle in Searches for New Molecular Species - the Case of H${}_2$C${}_3$O Isomers
• Photodissociation of small carbonaceous molecules of astrophysical interest
• A New and Simple Approach to Determine the Abundance of Hydrogen Molecules on Interstellar Ice Mantles
• Temperature Dependent Product Yields for the Spin Forbidden Singlet Channel of the C(3P) + C2H2 Reaction
• A CSO Search for $l$-C${}_3$H${}^{+}$: Detection in the Orion Bar PDR

Cited by in corpus (47)

• Discovery of the Pure Polycyclic Aromatic Hydrocarbon Indene ($c$-C${}_9$H${}_8$) with GOTHAM Observations of TMC-1
• Discovery of fulvenallene in TMC-1 with the QUIJOTE line survey
• Discovery of the propargyl radical (CH2CCH) in TMC-1: one of the most abundant radicals ever found and a key species for cyclization to benzene in cold dark clouds
• Molecules with ALMA at Planet-forming Scales (MAPS). IX. Distribution and Properties of the Large Organic Molecules HC${}_3$N, CH${}_3$CN, and $c$-C${}_3$H${}_2$
• A new look at sulphur chemistry in hot cores and corinos
• The sulphur saga in TMC-1: Discovery of HCSCN and HCSCCH
• Carbon-Chain Chemistry in the Interstellar Medium
• Isocyanogen formation in the cold interstellar medium
• Discovery of H${}_2$CCCH${}^{+}$ in TMC-1
• Cumulene carbenes in TMC-1: Astronomical discovery of $l$-H${}_2$C${}_5$
• Oxygen fractionation in dense molecular clouds
• The role of C/O in nitrile astrochemistry in PDRs and planet-forming disks
• Discovery of C5H+ and detection of C3H+ in TMC-1 with the QUIJOTE line survey
• A cold accretion flow onto one component of a multiple protostellar system
• Space and laboratory observation of the deuterated cyanomethyl radical HDCCN
• Chemical nitrogen fractionation in dense molecular clouds
• Discovery of HCCCO and C5O in TMC-1 with the QUIJOTE line survey
• Gas-grain model of carbon fractionation in dense molecular clouds
• An unbiased spectral line survey observation toward the low-mass star-forming region L1527
• Detection of Interstellar $E$-1-cyano-1,3-butadiene in GOTHAM Observations of TMC-1
• The ALMA-PILS survey: propyne (CH${}_3$CCH) in IRAS 16293$-$2422
• A sensitive 3 mm line survey of L483: a broad view of the chemical composition of a core around a Class 0 object
• Discovery of the cyclic C5H radical in TMC-1
• Discovery of CH2CCHC4H and a rigorous detection of CH2CCHC3N in TMC-1 with the QUIJOTE line survey
• Laboratory and astronomical discovery of the cyanovinyl radical H2CCCN
• The TW Hya Rosetta Stone Project IV: A hydrocarbon rich disk atmosphere
• ALMA high-resolution observations unveil planet formation shaping molecular emission in the PDS 70 disk
• Protoplanetary disks: Sensitivity of the chemical composition to various model parameters
• Influence of galactic arm scale dynamics on the molecular composition of the cold and dense ISM II. Molecular oxygen abundance
• Sensitivity Analysis of Aromatic Chemistry to Gas-Phase Kinetics in a Dark Molecular Cloud Model
• Astrochemical Modeling of Propargyl Radical Chemistry in TMC-1
• Vertical distribution of cyclopropenylidene and propadiene in the atmosphere of Titan
• First detection of doubly deuterated methyl acetylene (CHD2CCH and CH2DCCD)
• Constraints of the formation and abundances of methyl carbamate, a glycine isomer, in hot corinos
• Direct D-atom incorporation in radicals: An overlooked pathway for deuterium fractionation
• Chemical variations across the TMC-1 boundary: molecular tracers from translucent phase to dense phase
• Chemical exploration of Galactic cold cores
• The SOFIA Massive (SOMA) Star Formation Q-band follow-up I. Carbon-chain chemistry of intermediate-mass protostars
• New constraints on the initial parameters of low-mass star formation from chemical modeling
• Spatial distribution of C4H and c-C3H2 in cold molecular cores
• Interstellar Hydrocarbons: Degradation Chemistry in Diffuse Clouds
• Spatial distribution of organics in the Horsehead nebula: Signposts of chemistry driven by atomic carbon
• The evolution of C4H and c-C3H2 in molecular cores
• c-C3H2 deuteration towards prestellar and starless cores in the Perseus Molecular Cloud
• Chemistry of Dark Molecular Clouds
• Hydrocarbon complexity and photochemical shielding of prebiotic feedstock molecules in exoplanet atmospheres
• Carbon chain diversity in L1544 and IRAS 16293-2422: an astrochemical pathfinder study for the SKAO