The interstellar medium regulated by supernova remnants and bursts of star formation

Abstract

The time variation of the interstellar medium regulated by supernova remnants is studied by considering the interchange processes among six components: a warm gas, a general ambient gas, a hot gas, small clouds, molecular clouds and giant molecular clouds. Two interesting results are found. One is that the interstellar medium does not always attain a steady state such as a two- or three-phase model, but may exhibit a cyclic phase-change like a limit cycle or go to a runaway state. The other is that bursts of star formation from molecular clouds are expected if the gravitational instability of a cloud ensemble is considered.