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E.W. Pellegrini, M.S. Oey, P.F. Winkler, R.C. Smith & S. Points

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.

To cite this article

E.W. Pellegrini, M.S. Oey, P.F. Winkler, R.C. Smith & S. Points, «Escaping Radiation from Massive Star HII regions in the Magellanic Clouds», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 80 - Année 2011, 410 - 414 URL : https://popups.uliege.be/0037-9565/index.php?id=2888.

About: E.W. Pellegrini

Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI, USA

About: M.S. Oey

Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI, USA

About: P.F. Winkler

Department of Physics, Middlebury College, Middlebury, VT, USA

About: R.C. Smith

CTIO, Casilla 603, La Serena, Chile

About: S. Points

CTIO, Casilla 603, La Serena, Chile