  We develop PLATYPOS (PLAneTarY PhOtoevaporation Simulator), a python code to
perform planetary photoevaporative mass-loss calculations for close-in planets
with hydrogen-helium envelopes atop Earth-like rocky cores. With physical and
model parameters as input, PLATYPOS calculates the atmospheric mass loss and
with it the radius evolution of a planet over time, taking into account also
the thermal cooling and subsequent radius evolution of the planet. In
particular, we implement different stellar activity evolution tracks over time.
Our setup allows for a prediction of whether a planet can hold on to a
significant fraction of its atmosphere, or fully evaporates, leaving behind
only the bare rocky core. The user supplies information about the star-planet
system of interest, which includes planetary and host star parameters, as well
as the star's rotational and thus activity evolution. In addition, several
details for the evaporative mass-loss rate estimation can be chosen. This
includes the effective absorption cross-section for high energy photons, the
evaporation efficiency, and the hydrodynamic escape model.
