Large-scale coherent behaviour of star forming systems with feedbacks

Abstract

Abstract The star formation (SF) influenced by penetrating heating radiation is discussed. This radiation can affect SF in two ways: on the one hand, it can stimulate the SF process by provoking implosion of interstellar clouds which are optically thick to the heating radiation; on the other hand, the heating radiation exposing optically thin clouds neutralizes SF. So, heating radiation can be a link connecting a monitoring feedback loop of SF: birth of stars → generation of heating radiation → photoimplosion (or photoevaporation) of interstellar clouds → triggering (or inhibition) of star formation. The characteristic size of the region covered by the action of this feedback is of the order of the extinction length of the heating radiation. For UV photons with λ > 912 A passing in diffuse interstellar gas, it is about 0.3-1 kpc depending on gas density. This length is argued to be the length of synchronous behaviour of SF. The relation of this mechanism with the observed large-scale star-bursts is discussed.