Evaporation timescale of planets irradiated by a source of X-rays with L_X = 10²⁹ erg s^-1 (top row), pulsar wind L_sd = 4 × 10³² erg s (middle row) and L_sd = 10³⁴ erg s^-1 (bottom row). All figures on the left show the case for a very thick atmosphere holding 30% of the planet total mass. The right panels show the case for a thinner atmosphere of 1% of the total planet mass (which is a reasonable assumption for the atmospheric mass of Super-Earths; see Lopez & Fortney 2013; Elkins-Tanton & Seager 2008). The gray circles represent the mass and distance of four of the five pulsar planets with the exclusion of PSR B1257+12  a, which is too small to hold any atmosphere. The dots represent (from left to right): PSR B1257+12 b, PSR B1257+12 c, PSR J1719–1438 b, PSR B1620–26 b. The dotted black lines represent isochrones of 0.1, 1 and 10 Gyr (from bottom to top, respectively). The radius of all planets has been fixed to R_p = 2 R_⊕ and X_M = 10^-3. The evaporation timescales have been calculated with Eq. (24) (top figures) and 13 (middle and bottom figures).