Context : The Rosette molecular cloud is promoted as the archetype of a triggered star-formation site .
This is mainly due to its morphology , because the central OB cluster NGC 2244 has blown a circular-shaped cavity into the cloud and the expanding H II -region now interacts with the cloud .

Aims : Studying the spatial distribution of the different evolutionary states of all star-forming sites in Rosette and investigating possible gradients of the dust temperature will help to test the ’ triggered star-formation ’ scenario in Rosette .

Methods : We use continuum data obtained with the PACS ( 70 and 160 \mu m ) and SPIRE instruments ( 250 , 350 , 500 \mu m ) of the Herschel telescope during the Science Demonstration Phase of HOBYS .

Results : Three-color images of Rosette impressively show how the molecular gas is heated by the radiative impact of the NGC 2244 cluster .
A clear negative temperature gradient and a positive density gradient ( running from the H II -region/molecular cloud interface into the cloud ) are detected .
Studying the spatial distribution of the most massive dense cores ( size scale 0.05 to 0.3 pc ) , we find an age-sequence ( from more evolved to younger ) with increasing distance to the cluster NGC 2244 .
No clear gradient is found for the clump ( size-scale up to 1 pc ) distribution .

Conclusions : The existence of temperature and density gradients and the observed age-sequence imply that star formation in Rosette may indeed be influenced by the radiative impact of the central NGC 2244 cluster .
A more complete overview of the prestellar and protostellar population in Rosette is required to obtain a firmer result .