High-resolution UKIRT observations of circumnuclear star formation in M100

We present high-resolution, near-infrared imaging of the circumnuclear region of the barred spiral galaxy M100 (=NGC 4321), accompanied by near-infrared spec- troscopy.We identify a total of 43 distinct regions in the K-band image, and determine magnitudes and colours for 41 of them. By comparison with other near-infrared maps we also derive colour excesses and K-band extinctions for the knots. Combining the imaging and spectroscopic results, we conclude that the knots are the result of bursts of star formation within the last 15–25 Myr. We discuss the implications of these new results for our dynamical and evolutionary understanding of this galaxy.