Extinction of H ii regions in the Large Magellanic Cloud

The extinction properties of H ii regions in the Large Magellanic Cloud are investigated using radio continuum data obtained from the Molonglo Observatory Synthesis Telescope, digitized and calibrated Hα data and published Balmer decrement measurements. The resulting extinction–colour excess diagram suggests that (1) most H ii regions in the Magellanic Clouds have similar extinction properties to the Galactic ones, (2) all imaginable gas/dust configurations are possible, (3) the extinction of some highly reddened H ii region cores originates externally in cocoon shells.  The puzzle of different extinction–colour excess ratios of Galactic and extragalactic H ii regions is explained as being due to the different populations of observed samples rather than any intrinsic differences. The extinction of the observed Galactic H ii regions produced by foreground dust overwhelms the internal extinction, while the situation in the observed extragalactic H ii regions is just the opposite.