Francesco Paresce

 

Stellar properties and their distribution in the massive galactic cluster NGC 3603: pathfinder for Herschel

Matteo Correnti, Rossella Aversa

 

We have used new, deep, visible, and near-infrared observations of the central star cluster of the giant HII region NGC 3603 one of the most massive compact clusters in our galaxy with the WFC3 on HST and HAWK-I on the VLT to study in detail the physical properties of its stellar population and to relate these to those of the giant molecular cloud from whence they originate. Here, we show that after correction for differential extinction, field contamination and actively accreting stars, clear evidence remains for a continuous spread in pre-main sequence ages ranging from ~0.5 Myrs of the youngest objects to ~ 50 Myrs of the oldest within the temporal resolution available. Existing differences among presently available theoretical models account for the largest possible variation in shape of the measured age spreads within these limits The spatial distribution of the stellar ages and masses is consistent with the hypothesis that star formation occurs rapidly but randomly in space and time throughout the cluster during this relatively long time interval while the young stars in the core formed only recently in a burst in the last million years or so. This result has immediate consequences for its photon dominated surroundings that will soon be probed by Herschel during the GT key project.