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arXiv · 1803.10003

Electron Energy Distributions in HII Regions and Planetary Nebulae: kappa-Distributions Do Not Apply

B. T. Draine·C. D. Kreisch
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Abstract

Some authors have proposed that electron energy distributions in H II regions and planetary nebulae may be significantly nonthermal, and kappa-distributions have been suggested as being appropriate. Here it is demonstrated that the electron energy distribution function is extremely close to a Maxwellian up to electron kinetic energies ~13 eV in HII regions, and up to ~16eV in planetary nebulae: kappa-distributions are inappropriate. The small departures from a Maxwellian have negligible effects on line ratios. When observed line ratios in H II regions deviate from models with a single electron temperature, it must arise from spatial variations in electron temperature, rather than local deviations from a Maxwellian.

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B. T. Draine, C. D. Kreisch. 2018-07-20. Electron Energy Distributions in HII Regions and Planetary Nebulae: kappa-Distributions Do Not Apply. https://doi.org/10.3847/1538-4357%2Faac891

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