THE ULTRACOMPACT H-II REGION G45.45- A PEARL NECKLACE IN THE SKY(0.06)

We present new imaging data on the ultracompact H II region G45.45+0.0 6 at near- and mid-infrared wavelengths. High-resolution data were tak en in the H and K' bands using ESO's adaptive optics system ADONIS. Th e resulting images with a generic resolution of 0.'' 4 for the first t ime allow the resolution of the object into several single point-like sources. Additionally, we present images obtained in the mid-infrared at 3.5, 10, and 12 mu m. A Br gamma image was obtained to serve as a m easure for the extinction towards this region. We derive the physical properties of the point sources and show that some of them are young, massive stars. By combining our data with earlier VLA maps, we measure the extinction towards the region and discuss the history of the obje ct. Finally, we conclude that G45.45+0.06 is a young OB cluster simila r to the KL/BN Region in Orion and that sequential star formation is t he reason for its present morphology.