ROTATIONAL QUENCHING OF CO DUE TO H2 COLLISIONS

By Benhui Yang, P. Stancil, N. Balakrishnan, R. C. Forrey. 2010

264 citations recorded by the source corpus.

Rate coefficients for state-to-state rotational transitions in CO induced by both para- and ortho-H2 collisions are presented. The results were obtained using the close-coupling method and the coupled-states approximation, with the CO–H2 interaction potential of Jankowski & Szalewicz. Rate coefficients are presented for temperatures between 1 and 3000 K, and for CO(v = 0, j) quenching from j = 1–40 to all lower j′ levels. Comparisons with previous calculations using an earlier potential show some discrepancies, especially at low temperatures and for rotational transitions involving large |Δj|. The differences in the well depths of the van der Waals interactions and the anisotropy of the two potential surfaces lead to different resonance structures in the energy dependence of the cross sections which influence the low temperature rate coefficients. Applications to far infrared observations of astrophysical environments are briefly discussed.

Subfields: Astronomy and Astrophysics, Atmospheric Science

View Paper: https://www.semanticscholar.org/paper/7dd86e22f177da9e815eae4002cbbe3c7bf7fd6e

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In Astronomy and Astrophysics

1. D. Wilner
2. S. Andrews
3. A. Hughes
4. C. Qi
5. K. Rosenfeld
6. Jonathan P. Williams
7. T. Birnstiel
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In Atmospheric Science

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Citations in the corpus

• DEVELOPMENT OF THE MODEL OF GALACTIC INTERSTELLAR EMISSION FOR STANDARD POINT-SOURCE ANALYSIS OF FERMI LARGE AREA TELESCOPE DATA (2016, background): “The millimeter-wave emission of CO can trace H2 because the molecular hydrogen is its main collisional partner, and collisions excite its rotational transitions (Wilson et al. 1970; Yang et al. 2010).”
• The CO-to-H2 Conversion Factor (2013, unknown): “When Tex,J Tkin, usually Tex,J/Tex,J−1 1 for lines arising in the same parcel of gas, and the excitation of the J level is “subthermal” (note that this is not equivalent to TJ/TJ−1 < 1, as is sometimes used in the literature).”
• Cool outflows in galaxies and their implications (2020, background): “The critical density for the ground rotational transition of CO (at ν = 115.27 GHz) to collisions with molecular gas is ncr(H2) ≈ 2000 T−0.019100 cm−3 (Yang et al. 2010).”
• A SPATIALLY RESOLVED VERTICAL TEMPERATURE GRADIENT IN THE HD 163296 DISK (2013, methodology): “…using the non-local thermodynamic equilibrium (non-LTE) molecular excitation and radiative transfer package LIME (Brinch & Hogerheijde 2010) and molecular data from (A color version of this figure is available in the online journal.) the LAMDA database (Schöier et al. 2005; Yang et al. 2010).”
• Modelling CO emission – I. CO as a column density tracer and the X factor in molecular clouds (2010, unknown): “These are based on calculations by Yang et al. (2010).”
• Cool Gas in High-Redshift Galaxies (2013, background): “Collision rate coefficients for the excitation of CO by H2 are given by Flower et al. (1985) and Yang et al. (2010), and are typically ∼ 3 to 10 × 10−11 cm3 s−1 for the low–”