THE OXYGEN ABUNDANCE GRADIENT IN THE BARRED SPIRAL GALAXY NGC-4303

Imaging spectrophotometry in the nebular lines Halpha, Hbeta, [O III] lambda5007, and [N II] lambda6584, using a CCD camera and narrow-band interference filters, has been performed of 79 H II regions in the barred spiral galaxy NGC 4303 ranging from 0.4 to 2.8 R(eff) in galactocentric distances. Except for the bright emission in the nuclear region, the area within the bar radius is devoid of H II regions. The O/H abundance gradient was derived from the abundance indicators [O III]/Hbeta and [N II]/[O III]. The global abundance gradient derived from [O III]/Hbeta corresponds to DELTA log (O/H)/DELTAR = - 0.073 +/- 0.006 dex kpc-1, which is identical to that found in normal spiral galaxies like NGC 628, NGC 2997, and the Milky Way, i.e., there is no evidence of a "flatter" gradient due to the presence of a bar in NGC 4303. It is concluded that the presence of the bar has not affected the relative distribution of elements in the disk of NGC 4303 in the region beyond the stellar bar.