High spatial resolution radio continuum observations of compact H II regions in the Magellanic Clouds

Abstract

We present high spatial resolution observations of the 6 cm continuum emission of compact H II regions in well-known sites of massive star formation located in the Small and Large Magellanic Clouds. The observations include N81 in the SMC, and N4A, N83B, N11A, N160A and N159-5 in the LMC. Some of the compact H II regions are isolated, while others are embedded in more diffuse ionised regions. A description of the radio morphology of the sources, together with comparisons with other observations, is given in detail. The regions cover a wide range in size (from ∼0.1 to 7 pc), rms electron density (from ∼200 to 6500 cm-3), emission measure (from ∼3 × 10 5 to 2 × 107 pc cm-6), ionised gas mass (from ∼0.2 to 750 M⊙) and rate of Lyman continuum photons (from ∼3 × 1047 to 5 × 1049 s-1). The spectral types determined from the Lyman continuum fluxes are consistent with optical determinations. We have compared these Magellanic Cloud H II regions with their Galactic counterparts in terms of size, rms electron density and Lyman continuum flux. This comparison shows that their properties relate to each other in the same way as those in Galactic H II regions. © ESO 2005.