Professor Gilles Joncas of the Université Laval is studying each component of the interstellar medium (ionized gas, atomic gas, molecular gas and dust) over a wide range of wavelengths, from the visible to radio. The aim is to obtain a global (integrative) view, so as to obtain an evolutionary scenario for the various objects analysed, and a knowledge of the physical interactions between the different components. Broadly speaking, he and his colleagues are working on :