  Tidal heating of exomoons may play a key role in their habitability, since
the elevated temperature can melt the ice on the body even without significant
solar radiation. The possibility of life is intensely studied on Solar System
moons such as Europa or Enceladus, where the surface ice layer covers tidally
heated water ocean. Tidal forces may be even stronger in extrasolar systems,
depending on the properties of the moon and its orbit. For studying the tidally
heated surface temperature of exomoons, we used a viscoelastic model for the
first time. This model is more realistic than the widely used, so-called fixed
Q models, because it takes into account the temperature dependency of the tidal
heat flux, and the melting of the inner material. With the use of this model we
introduced the circumplanetary Tidal Temperate Zone (TTZ), that strongly
depends on the orbital period of the moon, and less on its radius. We compared
the results with the fixed Q model and investigated the statistical volume of
the TTZ using both models. We have found that the viscoelastic model predicts
2.8 times more exomoons in the TTZ with orbital periods between 0.1 and 3.5
days than the fixed Q model for plausible distributions of physical and orbital
parameters. The viscoelastic model gives more promising results in terms of
habitability, because the inner melting of the body moderates the surface
temperature, acting like a thermostat.
