Résumé
Rosette and Orion nebulae are two young massive star clusters in which no supernova explosion has occurred yet. That makes two very good candidates to study particle acceleration in a super bubble induces by the collective effects of stellar winds. Using data from Fermi-LAT and a phenomenological model, upper limits on the fraction of mechanical energy converted into accelerated particles have been obtained. The potential gamma-ray flux have been finally compared to the HESS-II and CTA Cherenkov telescopes sensitivities.