Oxygen abundance variations in the system of the two blue compact dwarf galaxies SBS 0335-052E and SBS0335-052W

We present 3.6 m ESO telescope spectroscopic observations of the system of the two blue compact dwarf galaxies SBS 0335-052W and SBS 0335-052E. The oxygen abundance in SBS 0335-052W is 12 + log O/H = 7.13 +/- 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 <= 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.