Radio Continuum Emission in the Resonance-Ring Galaxies NGC 1433 and NGC 6300

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NGC 1433 is a nearly face-on prototypical ringed, barred galaxy. It has a nuclear ring, an inner ring and an outer pseudoring. Also present are symmetrical spiral arcs, also called “plumes”, leading the central bar. Based on a study using multicolor surface photometry and Hα Fabry-Perot interferometry, Buta (1986) was able to associate each of the ring features with a specific orbital resonance. NGC 6300, having almost an identical Hubble type and distance to that of NGC 1433, provides for an ideal comparison. It has no nuclear or outer rings. However, the inner ring is quite broad and dusty (Buta 1987). Radio continuum data were obtained with the Australia Telescope Compact Array (ATCA) at 1.38 GHz (bandwidth = 128.0 MHz) with maximum baselines of 1.5 km, yielding a resolution of ∼ 30″ and r.m.s. noise per map of 0.2 mJy Beam⁻¹ for both of the galaxies. The Hα + N[II] images for both of the galaxies were obtained with the CTIO 1.5 m telescope.