FOREGROUND DUST AND GAS AND THE EXTINCTION CURVE OF THE LARGE MAGELLANIC CLOUD

We have compared the large-scale distributions of Galactic infrared and H I emission towards the Magellanic Clouds, resulting in estimates of the infrared foreground of the Clouds. For the Galactic gas-to-dust ration by mass we find 420 (+250, -120). From H I maps, we have also derived maps of the Galactic foreground colour excess towards the Magellanic Clouds on scales of 48 arcmin. Over the LMC surface the foreground reddening is not constant; it ranges from E(B - V) = 0.07 to 0.17 mag. For the SMC we find a foreground reddening E(B - V) = 0.07 to 0.09 mag. The amplitude of foreground reddening variations is probably much greater on smaller scales. Towards the 30 Doradus region, the mean foreground reddening is quite low. As a result, differences between the 30 Doradus and the average LMC extinction curves are much less than previously suggested.