The Self-Similar Structure of Molecular Clouds

Information on the structure of the interstellar clouds is contained in both spatial maps and spectral profiles of molecular gas emission lines. In this paper, we show that non gaussian aspects of line profiles are found at all scales. This excess wing emission is shown to be generated in dense gas. From a study of the moments of the lines as a function of scale size, we deduce a break-down in the exactness of self-similarity in the hierarchical structure of the interstellar clouds.