Atomic chemistry in turbulent astrophysical media. I. EFFECT OF Atomic cooling
- Lawrence Livermore National Laboratory, P.O. Box 808, L-038, Livermore, CA 94550 (United States)
- School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1494 (United States)
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)
We carry out direct numerical simulations of turbulent astrophysical media that explicitly track ionizations, recombinations, and species-by-species radiative cooling. The simulations assume solar composition and follows the evolution of hydrogen, helium, carbon, oxygen, sodium, and magnesium, but they do not include the presence of an ionizing background. In this case, the medium reaches a global steady state that is purely a function of the one-dimensional turbulent velocity dispersion, σ{sub 1D}, and the product of the mean density and the driving scale of turbulence, nL. Our simulations span a grid of models with σ{sub 1D} ranging from 6 to 58 km s{sup −1} and nL ranging from 10{sup 16} to 10{sup 20} cm{sup −2}, which correspond to turbulent Mach numbers from M = 0.2 to 10.6. The species abundances are well described by single-temperature estimates whenever M is small, but local equilibrium models can not accurately predict the global equilibrium abundances when M≳1. To allow future studies to account for nonequilibrium effects in turbulent media, we gather our results into a series of tables, which we will extend in the future to encompass a wider range of elements, compositions, and ionizing processes.
- OSTI ID:
- 22882281
- Journal Information:
- Astrophysical Journal, Vol. 801, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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