CI fine-structure emission from non-equilibrium PDRs

H. Störzer*, J. Stutzki, A. Sternberg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We present computations of [CI] 609 μm and 370 μm fine-structure line emission from non-equilibrium clouds which are suddenly shielded from initially intense far-ultraviolet radiation fields. After the incident UV fluxes are diminished the initially abundant C+ ions rapidly recombine, and the neutral atomic carbon is then slowly incorporated into CO molecules. The cloud cooling times are longer than the CI formation times, and intense [CI] emission persists as the clouds cool. The [CI] emission is thus much brighter from cooling clouds than in equilibrium photon dominated regions. We argue that if UV-scattering is inefficient the extended [CI] emission observed in star-forming regions may be better explained by nonequilibrium models than by steady state models.

Original languageEnglish
Pages (from-to)L13-L16
JournalAstronomy and Astrophysics
Issue number1
StatePublished - 1 Jul 1997


  • ISM: clouds
  • ISM: molecules
  • Line: formation
  • Radio lines: interstellar


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