Relative transit depth variation η computed with Eq. (51) as a function of the semimajor axis at 1 Gyr for planets of mass: 0.3 M_J (dotted), 0.5 M_J (dashed), 1 M_J (dash-dotted), 3 M_J (long dashed), 15 M_J (solid). The shaded area shows the zone where higher order terms become non-negligible. The decrease in the transit depth due to tidal interactions is smaller when the mass of the planet increases because massive objects are more compressible (see Sect. 4) and thus less subject to nonspherical deformations.