A radio model of the 30 Doradus region

The 30 Doradus region of the LMC has been mapped at 1415 MHz using the Fleurs Synthesis Telescope with a beamwidth of 50 arcsec. Comparisons with published maps of lower resolution at 408 MHz and 5 GHz suggest that emission from the 30 Dor nebula is entirely thermal. Neighbouring localized non-thermal sources can be identified but there is no widespread non-thermal component, apart from the background radiation from the LMC itself. A simple two-component model of the nebula fits the data well at all three frequencies; minimum electron densities and upper limits to the masses of the components may then be derived and the actual values estimated. Comparison of the 1415-MHz map with published Hβ isophotes enables the distribution and amount of obscuring matter to be determined. The mean extinction over the central region of the nebula is about 2 mag.