Tracing the general structure of galactic molecular clouds using Planck data - I. The Perseus region as a test case

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Erscheinungsjahr:
2015
Medientyp:
Text
Schlagworte:
  • turbulence
  • methods: data analysis
  • methods: statistical
  • ISM: clouds
  • ISM: structure
  • submillimetre: ISM
Beschreibung:
  • We present an analysis of probability distribution functions (pdfs) of column density in different zones of the star-forming region Perseus and its diffuse environment based on the map of dust opacity at 353 GHz available from the Planck archive. The pdf shape can be fitted by a combination of a lognormal function and an extended power-law tail at high densities, in zones centred at the molecular cloud Perseus. A linear combination of several lognormals fits very well the pdf in rings surrounding the cloud or in zones of its diffuse neighbourhood. The slope of the mean-density scaling law 〈ρ 〉 L∝Lα is steep (α = −1.93) in the former case and rather shallow (α = −0.77 ± 0.11) in the rings delineated around the cloud. We interpret these findings as signatures of two distinct physical regimes: (i) a gravoturbulent one which is characterized by nearly linear scaling of mass and practical lack of velocity scaling; and (ii) a predominantly turbulent one which is best described by steep velocity scaling and by invariant for compressible turbulence ⟨ρ⟩ L u 3 L /L
    ⟨ρ⟩LuL3/L
    , describing a scale-independent flux of the kinetic energy per unit volume through turbulent cascade. The gravoturbulent spatial domain can be identified with the molecular cloud Perseus while a relatively sharp transition to predominantly turbulent regime occurs in its vicinity.
Lizenz:
  • info:eu-repo/semantics/restrictedAccess
Quellsystem:
Forschungsinformationssystem der UHH

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oai:www.edit.fis.uni-hamburg.de:publications/e1a1c534-1ac5-4237-9dfb-052f90fe1ac9