Resumen:

Orbital resonances are dynamic mechanisms characterized by some strength capable of overcoming other perturbations, managing to keep the planetary systems captured in the resonance. There are two types of orbital resonances: mean motion resonances and secular resonances. We will discuss here the mean motion resonances. They are located at some specific values of the semimajor axes but they occupy a non-negligible region of the semimajor axis space, which crucially depends on the orbital eccentricities as can be seen in the structures shown in the figure corresponding to the mutual resonances in the HD74156 system. The existence of a certain resonant width added to the fact that there are mechanisms that lead to resonances (through orbital migration for example) makes resonant systems frequent. Several analytical models that have been proposed describe very well the resonant dynamics for low eccentricities and coplanar orbits, but when we go to inclined and eccentric orbits, the models become very complex, since they depend on long series expansions specific to each resonance, or they cannot be applied at all. The GBG21 semianalytical model (Gallardo, Beauge, Giuppone, 2021, A\\&A, 646, A148) is applicable in principle to all resonances without restrictions, it is especially good for eccentric and inclined systems and provides us with all the information that characterizes a resonance: location and width in semimajor axis, equilibrium points, libration periods, strengths and moreover, it describes very well the dynamical evolution in the vicinity of a resonance. This model also has the advantage of being implemented through a code that can be used without having to be a specialist in the subject. In this work we show how to apply the model to some planetary systems and how to interpret the results. We will also briefly discuss the more complex problems of three-body resonances and resonant chains.