SBSG 0335-052W: An extremely low metallicity dwarf galaxy

We present Multiple Mirror Telescope and Keck II telescope spectrophotometry and 3.5 m Calar Alto telescope R, I photometry of the western component of the extremely low metallicity blue compact galaxy SBSG 0335-052. The components, separated by 22 kpc, appear to be members of a unique, physically connected system. It is shown that SBSG 0335-052W consists of at least three stellar clusters and has the same redshift as SBSG 0335-052. The oxygen abundance in its two brightest knots is extremely low, 12 + log (O/H) = 7.22 ± 0.03 and 7.13 ± 0.08, respectively. These values are lower than in SBSG 0335-052 and are nearly the same as those in I Zw 18. The R-I color profiles are very blue in both galaxies because of the combined effects of ionized gas and a young stellar population emission. We argue that SBSG 0335-052W is likely to be a nearby, young dwarf galaxy.