Astrophysical: H II regions

  • Publication
    Photoionization Models of NGC 2363 and Their Implications for the Ionizing Star Cluster
    Using the photoionization code CLOUDY, we compute photoionization models for the giant extragalactic H II region NGC 2363 and compare them with optical...
  • Publication
    Photoionization Models of NGC 346
    We present spherically symmetric and plane-parallel photoionization models of NGC 346, an H II region in the Small Magellanic Cloud. The models are based on...
  • Publication
    Photoionization Models of NGC 346
    We have compared direct estimates of the ionizing photon flux from the stars observed within the H II region NGC 346 in the Small Magellanic Cloud with its...
  • Publication
    Photoionization of the Diffuse Interstellar Gas in Spirals by Lyman Photons Escaping from H II Regions
    The existence of an extended component of diffuse ionized gas (DIG) is a well-known property of spiral galaxies. The integrated ensuremath {{H}alpha }...
  • Publication
    Photoionized Herbig-Haro Objects in the Orion Nebula through Deep High Spectral Resolution Spectroscopy. II. HH 204
    We analyze the physical conditions, chemical composition, and other properties of the photoionized Herbig-Haro (HH) object HH 204 through Very Large Telescope...
  • Publication
    Physical conditions in the partially ionized zone of the Orion nebula
    We report the first reliable measurement of the nebular [O i] lambda 5577 emission line in the Orion nebula. Diagnostic diagrams based on the [O i] lambda...
  • Publication
    Physical Scenarios for Supersonic Gas Flows Observed in H II Regions
    Line profiles in ensuremath {{H}alpha } emission from H II region populations in spiral galaxies show emission features at +/-50 km/s from the main emission...
  • Publication
    Populations of High-Luminosity Density-bounded H II Regions in Spiral Galaxies: Evidence and Implications
    We present evidence that the H II regions of high luminosity in disk galaxies may be density bounded, so that a significant fraction of the ionizing photons...
  • Publication
    Primordial Helium Abundance Determinations
    Based on the best observations of extragalactic H II regions of low metallicity available in the literature we redetermine the primordial helium abundance, Y[p]...