Oxygen abundance variations in the system of the two blue compact dwarfgalaxies SBS 0335-052E and SBS 0335-052W

We present 3.6 m ESO telescope spectroscopic observations of the system of the two blue compact dwarf galaxies SBS 0335-052 W and SBS 0335-052 E. The oxygen abundance in SBS 0335-052W is $12 + \log\,{\rm O/H} = 7.13 \pm 0.08$, confirming that this galaxy is the most metal-deficient emission-line galaxy known. We find that the oxygen abundance in SBS 0335-052E varies from region to region in the range from 7.20 to 7.31, suggesting the presence of an abundance gradient over a spatial scale of $\la$1 kpc. Signatures of early carbon-type Wolf-Rayet stars are detected in cluster #3 of SBS 0335-052 E, corresponding to the emission of 20 to 130 WC4 stars, depending on the adopted luminosity of a single WC4 star in the C IV $\lambda$4658 emission line.