LUMINOSITY-METALLICITY RELATIONS FOR BLUE COMPACT DWARF GALAXIES IN THE OPTICAL AND NEAR-INFRARED

In this paper, we present systematic studies on the B-, R- and K(s)-band luminosity-metallicity (L-Z) relations for a set of metal-poor, blue compact dwarf galaxies (BCDs). Metallicity is derived by using both the empirical N2 and the direct T(e) methods. Our work reconciles contradictory results obtained by different authors and shows that the L-Z relationship does also hold for BCDs. The empirical N2-based slope of the L-Z relation, for each photometric band, is consistent with the T(e)-based one. We confirm that the slope of the L-Z relation is shallower in the near-infrared than that in the optical. Our investigations on the correlations between the LB-Z relation residuals and different galactic parameters show that the star formation activities could be a cause of the large scatter in the optical L-Z relationships, whereas the internal absorption might be another possible contributing factor.