The Herschel view of star formation in the Rosette molecular cloud under the influence of NGC 2244
Olofsson, G.; Abergel, A.; Hill, T.; Roussel, H.; André, Ph.; Könyves, V.; Testi, L.; Sauvage, M.; Wilson, C. D.; Teyssier, D.; Schneider, N.; Csengeri, T.; Bontemps, S.; Panuzzo, P.; White, G.; Zavagno, A.; Griffin, M.; Men'shchikov, A.; Didelon, P.; Bernard, J. -Ph.; Kirk, J.; Motte, F.; Pezzuto, S.; Spinoglio, L.; Ward-Thompson, D.; Hennemann, M.; Li, J. Z.; Minier, V.; Cox, P.; Huang, M.; Molinari, S.; Russeil, D.; Marston, A.; Saraceno, P.; di Francesco, J.; Sadavoy, S.; Martin, P.; Persi, P.; Sibthorpe, B.; Vavrek, R.; Baluteau, J. -P.; Hargrave, P.; Leeks, S.; Woodcraft, A.; Gastaud, R.; di Giorgio, A. -M.
France, Canada, Italy, United Kingdom, China, Spain, Sweden, Germany
Abstract
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 μm) and SPIRE instruments (250, 350, 500 μm) 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.