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M.S. Oey (STScI), J.C. Shields (Ohio U.), M.A. Dopita (ANU/MSSSO), R.C. Smith (CTIO)
DEM 301 (N70) in the Large Magellanic Cloud is a well-known superbubble presumably created by the stellar winds and supernovae of the enclosed OB association LH 114. The dominant stars presently found in this association are of spectral type O3~If* and O5:~III. The photometry for these stars implies ionizing luminosities \log L\rm LyC ~ 39.2, yet the observed H\alpha emission from the nebula implies only \log L\rm LyC = 38.0. It would therefore seem likely that the nebula should be density-bounded. However, here we present emission-line spectra and photoionization models of DEM~301 that show this object to be primarily radiation-bounded. We present narrow-band images of the object and discuss how the nebula can leak the majority of its ionizing photons but still be radiation-bounded. We note that signatures of density-bounded nebulae are therefore not required evidence of existing photon leakage.
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