Oxygen fractionation in dense molecular clouds

Abstract

We have developed the first gas-grain chemical model for oxygen fractionation (also including sulphur fractionation) in dense molecular clouds, demonstrating that gas-phase chemistry generates variable oxygen fractionation levels, with a particularly strong effect for NO, SO, O2, and SO2. This large effect is due to the efficiency of the neutral 18O + NO, 18O + SO, and 18O + O2 exchange reactions. The modeling results were compared to new and existing observed isotopic ratios in a selection of cold cores. The good agreement between model and observations requires that the gas-phase abundance of neutral oxygen atoms is large in the observed regions. The S16O/S18O ratio is predicted to vary substantially over time showing that it can be used as a sensitive chemical proxy for matter evolution in dense molecular clouds.

arXiv comment22 pages, 5 figures

References in corpus (32)

• The 2014 KIDA network for interstellar chemistry
• Physical structure and CO abundance of low-mass protostellar envelopes
• Gas and grain chemical composition in cold cores as predicted by the Nautilus 3-phase model
• Binding energies: new values and impact on the efficiency of chemical desorption
• On the reservoir of sulphur in dark clouds : chemistry and elemental abundance reconciled
• Modeling Complex Organic Molecules in dense regions: Eley-Rideal and complex induced reaction
• Weeds: a CLASS extension for the analysis of millimeter and sub-millimeter spectral surveys
• A line confusion limited millimeter survey of Orion KL (I): sulfur carbon chains
• The IRAM-30m line survey of the Horsehead PDR: II. First detection of the l-C3H+ hydrocarbon cation
• Isotopic fractionation of carbon, deuterium and nitrogen : a full chemical study
• Herschel measurements of the D/H and 16O/18O ratios in water in the Oort-cloud comet C/2009 P1 (Garradd)
• Sulphur chemistry in the L1544 pre-stellar core
• A New Reference Chemical Composition for TMC-1
• Nitrogen isotopic ratios in Barnard 1: a consistent study of the N2H+, NH3, CN, HCN and HNC isotopologues
• The interstellar chemistry of C3H and C3H2 isomers
• Ortho-H2 and the Age of Interstellar Dark Clouds
• The interstellar chemistry of H2C3O isomers
• A line confusion-limited millimeter survey of Orion KL. III. Sulfur oxide species
• Discovery of interstellar isocyanogen (CNCN): further evidence that dicyanopolyynes are abundant in space
• High-precision C17O, C18O and C16O measurements in young stellar objects: analogues for CO self-shielding in the early solar system
• Ionization fraction and the enhanced sulfur chemistry in Barnard 1
• The origin of gas-phase HCO and CH3O radicals in prestellar cores
• Discovery of the elusive radical NCO and confirmation of H2NCO+ in space
• Detection of interstellar HCS and its metastable isomer HSC: new pieces in the puzzle of sulfur chemistry
• Carbon Isotope and Isotopomer Fractionation in Cold Dense Cloud Cores
• Review of OCS gas-phase reactions in dark cloud chemical models
• Depletion of heavy nitrogen in the cold gas of star-forming regions
• Is the Sun Lighter than the Earth? Isotopic CO in the Photosphere, Viewed through the Lens of 3D Spectrum Synthesis
• A New and Simple Approach to Determine the Abundance of Hydrogen Molecules on Interstellar Ice Mantles
• Ion-molecule reactions involving HCO${}^{+}$ and N${}_2$H${}^{+}$: Isotopologue equilibria from new theoretical calculations and consequences for interstellar isotope fractionation
• Methyl cyanide (CH3CN) and propyne (CH3CCH) in the low mass protostar IRAS 16293-2422
• Prestellar core modeling in the presence of a filament - The dense heart of L1689B

Cited by in corpus (26)

• Astrochemistry and compositions of planetary systems
• Gas phase Elemental abundances in Molecular cloudS (GEMS). II. On the quest for the sulphur reservoir in molecular clouds: the $H_{2}S$ case
• Gas phase Elemental abundances in Molecular cloudS (GEMS) VII. Sulfur elemental abundance
• Direct measurements of carbon and sulfur isotope ratios in the Milky Way
• Gas phase Elemental abundances in Molecular cloudS (GEMS). IV. Observational results and statistical trends
• Formation of the Musca filament: Evidence for asymmetries in the accretion flow due to a cloud-cloud collision
• Gas-grain model of carbon fractionation in dense molecular clouds
• Spatially resolved carbon and oxygen isotopic ratios in NGC 253 using optically thin tracers
• C${}^{18}$O emission as an effective measure of gas masses of protoplanetary disks
• Sulphur and carbon isotopes towards Galactic centre clouds
• Sulphur-rich cold gas around the hot core precursor G328.2551-0.5321. An APEX unbiased spectral survey of the 2 mm, 1.2 mm, and 0.8 mm atmospheric windows
• Molecule dependent oxygen isotopic ratios in the coma of comet 67P/Churyumov-Gerasimenko
• A sensitive 3 mm line survey of L483: a broad view of the chemical composition of a core around a Class 0 object
• The water line emission and ortho-to-para ratio in the Orion Bar photon-dominated region
• Detection of HC18O+ in a protoplanetary disk: exploring oxygen isotope fractionation of CO
• Detection of deuterated molecules, but not of lithium hydride, in the z=0.89 absorber toward PKS1830-211
• Chemical compositions of five Planck cold clumps
• Sulfur isotope ratios in the Large Magellanic Cloud
• Molecular isotopologue measurements toward super star clusters and the relation to their ages in NGC253 with ALCHEMI
• PRODIGE - envelope to disk with NOEMA: V. Low 12C/13C ratios for CH3OH and CH3CN in hot corinos
• Cosmic-ray ionisation rate in low-mass cores: the role of the environment
• Mapping Synthetic Observations to Prestellar Core Models: An Interpretable Machine Learning Approach
• First detection of HS2 in a cold dark cloud
• Theoretical studies of carbon isotopic fractionation in reactions of C with C${}_2$: dynamics, kinetics, and isotopologue equilibria
• ${}^{18}$O${/}^{17}$O abundance ratio toward a sample of massive star forming regions with parallax distances
• Fine-tuning the complex organic molecule formation: sulfur and CO ice as regulators of surface chemistry