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- Volume 80 - Année 2011
- Escaping Radiation from Massive Star HII regions in the Magellanic Clouds
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Escaping Radiation from Massive Star HII regions in the Magellanic Clouds
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Abstract
We present a novel approach for distinguishing density-bounded vs radiation bounded HII regions based on [SII]/Halpha and [SII]/[OIII] ratio maps. We find most HII regions fall into one of three categories: radiation bounded, open blister type, and density bounded. Our approach directly diagnoses the existence of ionization fronts around massive stars, revealing a significant number of HII regions to be density bounded. Furthermore, we can place a lower limit on the fraction of ionizing photons escaping each region yielding values consistent with other methods, with direct implications for the ionization of the Warm Interstellar Medium and reionization of the universe at high redshift. We conclude that the three morphological classifications are correlated with the observed N(HI) column density and Halpha luminosity, however a more filamentary structure of the LMC does not lead to higher HII escape fractions than in the SMC.
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A propos de : E.W. Pellegrini
Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI, USA
A propos de : M.S. Oey
Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI, USA
A propos de : P.F. Winkler
Department of Physics, Middlebury College, Middlebury, VT, USA
A propos de : R.C. Smith
CTIO, Casilla 603, La Serena, Chile
A propos de : S. Points
CTIO, Casilla 603, La Serena, Chile