Photoelectric emission from interstellar dust: Grain charging and gas heating

Joseph C. Weingartner, B. T. Draine

Research output: Contribution to journalArticle

311 Scopus citations

Abstract

We model the photoelectric emission from and charging of interstellar dust and obtain photoelectric gas heating efficiencies as a function of grain size and the relevant ambient conditions. We employ improved estimates for photoelectric thresholds, yields, and electron capture rates. Using realistic grain size distributions, we evaluate the net gas heating rate for various interstellar environments and find less heating for dense regions characterized by Rv = 5.5 than for diffuse regions with Rv = 3.1. We provide fitting functions that reproduce our numerical results for photoelectric heating and recombination cooling for a wide range of interstellar conditions. Finally, we investigate the potential importance of photoelectric heating in H II regions, including the warm ionized medium. We find that photoelectric heating could be comparable to or exceed heating due to photoionization of H for high ratios of the radiation intensity to the gas density. We also find that photoelectric heating by dust can account for the observed variation of temperature with distance from the Galactic midplane in the warm ionized medium.

Original languageEnglish (US)
Pages (from-to)263-281
Number of pages19
JournalAstrophysical Journal, Supplement Series
Volume134
Issue number2
DOIs
StatePublished - Jun 2001

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Dust, extinction
  • H II regions
  • ISM: clouds

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