Gas and grain chemical composition in cold cores as predicted by the Nautilus three-phase model

By M. Ruaud, V. Wakelam, F. Hersant. 2016

211 citations recorded by the source corpus.

We present an extended version of the 2-phase gas-grain code NAUTILUS to the 3-phase modelling of gas and grain chemistry of cold cores. In this model, both the mantle and the surface are considered as chemically active. We also take into account the competition among reaction, diffusion and evaporation. The model predictions are confronted to ice observations in the envelope of low-mass and massive young stellar objects as well as toward background stars. Modelled gas-phase abundances are compared to species observed toward TMC-1 (CP) and L134N dark clouds. We find that our model successfully reproduces the observed ice species. It is found that the reaction-diffusion competition strongly enhances reactions with barriers and more specifically reactions with H2, which is abundant on grains. This finding highlights the importance to have a good approach to determine the abundance of H2 on grains. Consequently, it is found that the major N-bearing species on grains go from NH3 to N2 and HCN when the reaction-diffusion competition is accounted. In the gas-phase and before few 10^5 yrs, we find that the 3-phase model does not have a strong impact on the observed species compared to the 2-phase model. After this time, the computed abundances dramatically decrease due to the strong accretion on dust, which is not counterbalanced by the desorption less efficient than in the 2-phase model. This strongly constrains the chemical-age of cold cores to be of the order of few 10^5 yrs.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/b0a374015c1fccaa4646a40f9a058bf6fc491779

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In Astronomy and Astrophysics

1. J. Loison
2. M. Ruaud
3. V. Wakelam
4. P. Caselli
5. R. Méreau
6. A. Vasyunin
7. P. Gratier
8. A. Jaziri

In Spectroscopy

1. J. Loison
2. P. Caselli
3. M. Ruaud
4. V. Wakelam
5. I. Jiménez-Serra
6. Franccois Dulieu
7. A. Vasyunin

Citations in the corpus

• Binding energies: New values and impact on the efficiency of chemical desorption (2017, methodology): “All models we have presented here have been obtained with a fraction of the diffusion energy to the binding energy at the surface of 0.4 following Ruaud et al. (2016).”
• On the reservoir of sulphur in dark clouds : chemistry and elemental abundance reconciled (2017, methodology): “We take for the surface a value of this ratio of 0.4 as suggested by experiments and theoretical work made on H (see Ruaud et al. 2016, and reference therein), CO and CO2 (see Karssemeijer & Cuppen 2014).”
• Formation of Complex Molecules in Prestellar Cores: A Multilayer Approach (2017, result): “This approach is qualitatively similar to that described by (e.g. Taquet et al. 2012), Garrod (2013) and Ruaud et al. (2016).”
• Discovery of the Pure Polycyclic Aromatic Hydrocarbon Indene (c-C9H8) with GOTHAM Observations of TMC-1 (2021, unknown): “1 code (Ruaud et al. 2016).”