Kolmogorov's normal form for equations of motion with dissipative effects

We focus on the equations of motion related to the "dissipative spin-orbit model", which is commonly studied in Celestial Mechanics. We consider them in the more general framework of a 2n-dimensionalaction-angle phase space. Since the friction terms are assumed to be linear and isotropic with respect to the action variables, the Kolmogorov's normalization algorithm for quasi-integrable Hamiltonians can be easily adapted to the dissipative system considered here. This allows us to prove the existence of quasi-periodic invariant tori that are local attractors