Reddenings and metallicities in the LMC and SMC from Stroemgren CCD photometry

Abstract

The individual reddenings for B stars in two fields in the Small Magellanic Cloud (SMC) and two fields in the Large Magellanic Cloud (LMC) are determined by means of Stroemgren uvby CCD photometry. In both LMC fields we find a foreground reddening of E(B-V) = 0.085 +/- 0.02, and for the SMC fields we find E(B-V) = 0.070 +/- 0.02. In addition to the foreground reddening we find contributions from reddening intrinsically in the Clouds up to E(B-V) ~ 0.21. The intrinsic contribution is not correlated with position within our 6 x 4.5 arcmin CCD fields but varies in an essentially random way. Unless the reddening is measured for a particular object, it will be uncertain by +/- 0.035 in E(B-V) (best case, far from the central bars) to more than +/- 0.10 (close to the central bars). The Stroemgren vby photometry has been used to derive metallicities for GK giant stars in the observed fields. Adopting average reddenings we obtain mean metallicities which are consistent with those found from spectroscopic studies of F and G supergiants but with a considerable scatter, from [Fe/H]~ -2.0 to > 0. A significant fraction of the scatter is, however, due to reddening variations rather than being intrinsic. The possible existence of high metallicity stars should be investigated further using spectroscopic methods.