Advisor: Dr. Antonio Mario Magalhaes
 

ABSTRACT

We have studied the interstellar dust in the Small Magellanic Cloud employing visible polarimetry and ultraviolet spectrophotometry. The SMC typical extinction curve is not fitted by the standard grain model that uses a power law size distribution of bare grains. We suggest some modifications in order to best fit the data. Only one star presents the 2175Á bump in the extinction. It seems to be shifted to bluer wavelengths with relation to its mean Galactic value, whicb cannot be reproduced by spberical graphite grains.

The analysis of the polarimetric data by the most popular grain models indicates that the grains seem to be generally smaller in the SMC than in the Milky Way Galaxy. However, some stars show the wavelength of the maximum polarization, lambda_max, at wavelengths similar to the Galaxy, albeit with a distinct relation between the curve width and lambda_max. The polarization curves of such stars are not well fitted by the grain models. In addition, there is a possible correlation between the spectral dependence of the polarization and that of the extinction curve, in sense that stars with smaller lambda_maxdo not present the 2175Á bump.

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