Tidal evolution of the Kepler-10 system

We investigate by numerical methods the tidal evolution of the Kepler-10 system, which consists of an inner rocky planet and an outer terrestrial planet, by considering various initial eccentricity pairs that follow conservation of angular momentum of the system. Our results cover the range of all reasonable initial eccentricities with various mass ratios of the two planets for the Kepler-10 system; all initial eccentricity pairs can produce the present observed orbits within certain errors. Additional simulations with alternate values of dissipation factor Q(1)' are carried out, where the results may be indicative of the possible range 50 <= Q(1)' <= 500. Moreover, considering the density of the terrestrial planets and the previous models, we provide a possible constraint on the mass of Kepler-10c of 7M(circle plus) <= m(2) <= 20M(circle plus). Finally, we propose a possible planetary formation scenario for the Kepler-10 system: both planets may form from a distant region in the disc, then the inner planet may experience planet-planet scattering, following as tidal decay and circulation. However, the outer companion may undergo mainly disc migration, judging from our model.