Comet P/Gehrels 3: spectroscopic observations and nucleus models

In the framework of an observational campaign for increasing the knowledge on the relationship between cometary nuclei and asteroids, we performed spe ctroscopic observations of P/Gehrels 3. The Jupiter family comet P/Gehrels 3 moves on a particular orbit, with a very high Tisserand invariant with re spect to Jupiter, that makes the encounters with the planet very effective. This implies that the comet spends part of its life as a temporary satelli te of Jupiter, on an orbit that shows similarity with those of Trojans. Thi s comet has been observed when it was far from the Sun, with the aim to acq uire data on the nucleus status. In order to study from a theoretical point of view the possible status and evolution of a body on this orbit we have developed different nucleus models using a numerical code for the thermal e volution of the nucleus.