Evolution of orbital separation and unbound mass fraction of the envelope in the simulations, taking magnetic fields into account (MHD) and neglecting magnetic fields (non-MHD). In both simulations, MHD and non-MHD, local thermalization of released recombination energy is assumed. For the non-MHD simulation, we show only data until t = 3568 d. The unbound mass fraction is computed according to a kinetic-energy criterion (orange) and an internal-energy criterion, which additionally includes ionization energy released in recombination processes (gray).