  Context. With the detection of thousands of exoplanets, characterising their
dynamical evolution in detail represents a key step in the understanding of
their formation. Studying the dissipation of tides occurring both in the host
star and in the planets is of great relevance in order to investigate the
distribution of the angular momentum occurring among the objects populating the
system and to studying the evolution of the orbital parameters. From a
theoretical point of view, the dissipation of tides throughout a body may be
studied by relying on the so-called phase or time-lag equilibrium tides model
in which the reduced tidal quality factor Q'p, or equivalently the product
between the love number and the time lag (k2DeltaT), describe how efficiently
tides are dissipated within the perturbed body. Constraining these factors by
looking at the current configuration of the exoplanetary system is extremely
challenging, and simulations accounting for the evolution of the system as a
whole might help to shed some light on the mechanisms governing this process.
Aims. We aim to constrain the tidal dissipation factors of hot-Jupiter-like
planets by studying the orbital evolution of Kepler-91b. Methods. We firstly
carried out a detailed asteroseismc characterisation of Kepler-91 and computed
a dedicated stellar model using both classical and astereoseismic constraints.
We then coupled the evolution of the star to the one of the planets by means of
our orbital evolution code and studied the evolution of the system by
accounting for tides dissipated both in the planet and in the host star.
Results. We found that the maximum value for k2DeltaT (or equivalently the
minimum value for Q'p) determining the efficiency of equilibrium tides
dissipation occurring within Kepler-91b is 0.4 pm 0.25 s (4.5+5.8 * 10^5).
