Abstract
This is a report in advance of an in-depth analysis of the extragalactic giant H 0 region NGC 604 in M33. This object is the prototypical scale OB association and its properties (massive stellar content, young, and low foreground extinction) make it an ideal object to a detailed analysis. Here, we present the very early results of new Hubble Space Telescope observations obtained with the NICMOS Camera 2 and the Advanced Camera for Surveys (ACS), namely: (a) the discovery of four new red supergiant star candidates which are closely (parsec-scale) associated to known Wolf-Rayet stars; (b) the discovery of a large population of young stellar objects associated to the previously known molecular cores and regions with high extinction, some of them being high luminosity objects.
