Normalized values of the secular rate of change of the planetary semimajor axis, as function of the binary mass ratio and α. Each panel shows results for different eccentricities, assumed fixed for this calculation. Blue tones denote regions where the planet experiences an inward orbital migration, while red tone identify regions where the migration is outward. The primordial parameters of Kepler-38 are again highlighted in the top panel with a filled white circle and marked as “K38”.