Near-Infrared Observations of Circumnuclear Star Formation in NGC 3351, NGC 3504, and NGC 5248

High-resolution near-infrared (J and K band) images of the inner 50" of the hotspot galaxies NGC 3351, NGC 3504, and NGC 5248 were used to measure colors of star-forming regions. The hotspot colors are consistent with ages of approximately 10⁷ yr. Near-infrared (MR) peaks in NGC 5248 are coincident with published HST UV peaks. In NGC 3351, MR hotspots coincide with published Hα peaks, which are offset from CO twin peaks. In addition, bright K-band emission exists without optical or gas peak counterparts, and reveals the underlying inner Lindblad resonance ring and older star formation sites. Published CO maps of NGC 3351 were used to determine that the Q stability parameter is less than 1.4 in the ring, consistent with star formation. In NGC 3504, a ring of star formation is revealed in the (J- K) map at the location of the inner inner Lindblad resonance, with a two-arm spiral originating outside of the ring. Circumnuclear star formation rates are 0.4 Msun yr⁻¹ in NGC 3351 and 1.5Msun yr⁻¹ in NGC 5248; these rates may scale with galaxy Hubble type and total mass. We also observed the barred spirals NGC 4123, 4303, 5350, and 5921. None of these show evidence of circumnuclear rings in the MR.