Abstract
New optical and near-infrared observations of the Galactic H II region NGC 3603 have been obtained in order to explore the interaction of the central starburst cluster HD 97950 with the remains of the molecular cloud and the formation of new generations of OB-type stars. Ample evidence for continuous stellar formation activity proceeding from north to south over the past three to six million years is presented. K-band excesses are found in 50 objects which are the youngest OB-type stars in the region. Nearly 80% is clustered or associated to signposts of recent star formation. Several sources are found near the tips of the ionization fronts produced by HD 97950. Some of these are young OB stars with water masers in their vicinity and/or associated to isolated radio-continuum emission peaks. Near the centre of the active star formation region that is further away from HD 97950, the Irs 9 cluster, 12 OB-type stars (out of 16) with large excess emission beyond 2 μm are found within a 15 arcsec radius. The most massive star of this new stellar generation in NGC 3603 is an O5--O6 star.
