  Despite the identification of a great number of Jupiter-like and Earth-like
planets at close-in orbits, the number of "hot Neptunes" - the planets with
0.6-18 times of Neptune mass and orbital periods less than 3 days - turned out
to be very small. The corresponding region in the mass-period distribution was
assigned as the "short-period Neptunian desert". The common explanation of this
fact is that the gaseous planet with few Neptune masses would not survive in
the vicinity of host star due to intensive atmosphere outflow induced by
heating from stellar radiation. To check this hypothesis we performed numerical
simulations of atmosphere dynamics for a hot Neptune. We adopt the previously
developed self-consistent 1D model of hydrogen-helium atmosphere with
suprathermal electrons accounted. The mass-loss rates as a function of orbital
distances and stellar ages are presented. We conclude that the desert of
short-period Neptunes could not be entirely explained by evaporation of planet
atmosphere caused by the radiation from a host star. For the less massive
Neptune-like planet, the estimated upper limits of the mass loss may be
consistent with the photo-evaporation scenario, while the heavier Neptune-like
planets could not lose the significant mass through this mechanism. We also
found the significant differences between our numerical results and widely used
approximate estimates of the mass loss.
