Thermal evolution of the Centaur object 5145 Pholus

We present the results obtained by the simulations of different thermal models of 5145 Pholus, one of the known Centaurs. Pholus's orbit is highly eccentric, similar to that of comets, but its dimension is more similar to larger asteroids. Pholus cannot be clearly numbered in either class. The most likely source of Centaurs is the Edgeworth-Kuiper belt: dynamical studies and physical properties suggest that Pholus recently entered the planetary zone. Here we assume that the nature of Pholus is that of a cometary body made of different ices and dust. We have computed the thermal evolution of this object under different conditions: as a "new" object, namely an undifferentiated body, and an "old" one, differentiated and aged in the Kuiper belt. We have tried to see also the effects induced by the presence of an organic dust on the overall evolution. Both the "new" and the "old" object show low, but different, levels of gas activity.