  Terrestrial planets formed within gaseous protoplanetary disks can accumulate
significant hydrogen envelopes. The evolution of such an atmosphere due to XUV
driven evaporation depends on the activity evolution of the host star, which
itself depends sensitively on its rotational evolution, and therefore on its
initial rotation rate. In this letter, we derive an easily applicable method
for calculating planetary atmosphere evaporation that combines models for a
hydrostatic lower atmosphere and a hydrodynamic upper atmosphere. We show that
the initial rotation rate of the central star is of critical importance for the
evolution of planetary atmospheres and can determine if a planet keeps or loses
its primordial hydrogen envelope. Our results highlight the need for a detailed
treatment of stellar activity evolution when studying the evolution of
planetary atmospheres.
