Electron Energy Distributions in H ii Regions and Planetary Nebulae: κ-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 κ-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 of in H ii regions, and up to in planetary nebulae: κ-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.

Original languageEnglish (US)
Article number30
JournalAstrophysical Journal
Volume862
Issue number1
DOIs
StatePublished - Jul 20 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • H II regions
  • ISM: general
  • atomic processes
  • planetary nebulae: general
  • plasmas

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