SIMBAD references

We investigate the surface composition of Centaurs and Trans-Neptunian objects (TNOs) to get constraints on the formation and the evolution of this population. We report visible and near-infrared spectroscopic observations of the Plutino 55638 (2002 VE₅) obtained at VLT-ESO. The surface model has been computed using two types of radiative transfer models considering geographical and intimate mixtures of different materials. The obtained results have been compared with those for objects having near-infrared spectra available in the literature. The whole sample of 32 objects has been analyzed, in particular the presence of ices has been investigated in relation to their surface characteristics (taxonomic groups), their dynamical properties and the object sizes. The main result is the clear detection of H₂0 and CH₃OH (or a similar molecule) on the surface of 55638. The analysis of the whole sample shows that there are no obvious trends, but the larger objects seem to be icier. The BB group also seems to show more ice content on the surface, whereas RR group may contain more organic material.