High mass star and cluster formation: new insights from Herschel

The HOBYS key program essentially imaged with Herschel all of the regions forming OB-type stars at distances less than 3 kpc from the Sun. This survey allows to statistically study the formation of 10-20 Msun stars and confirms that high-mass pre-stellar cores do not exist. HOBYS also reveals mini-starburst cloud ridges, which have high mean densities and are the privileged sites for the formation of high-mass stars.