In the work presented here, we have used interferometry as a Swiss knife allowing us to make contributions in a number of relevant astrophysical scenarios of research where high angular resolution provides a privileged insight. Both stellar and substellar objects are the targets of our studies, which cover from asymptotic giant branch (AGB) and red supergiant (RSG) stars with very extended and cool atmospheres to ultracool low-mass objects which show extreme magnetic activity. The extraordinary resolution provided by present instrumentation, both in radio and infrared, along with their increasing sensitivity allow us to investigate.... [Leer más...]