Alfaro, E.; Elías, F.
Lecture Notes and Essays in Astrophysics, vol. 2, p. 111-126.
Binary stars, trapezium systems, star clusters, OB associations, star complexes, supercomplexes and flocculent spiral arms: all of them represent different spatial scales of coherency in the star formation process. One of the main questions in the study of how the stars are formed in galaxies is how to connect all these different scales into a basic scenario. During the last twenty years many people have been working to give a response to this problem, and now we have some answers. In this paper we discuss the structure in cascade of the different star formation scales and its connection with the arrangement of the galactic gas into clouds. We also analyze in depth two star complexes: one located in the spiral galaxy NGC 6946, and another located in the Milky Way with its center is close to the Sun, known as the Gould Belt.