Discovery of Two TNO-like Bodies in the Asteroid Belt

Two extremely red main-belt asteroids, 203 Pompeja and 269 Justitia, were identified from combined visible and near-infrared spectroscopic observations collected at the Infra-red Telescope Facility (IRTF) and Seoul National University Astronomical Observatory (SAO). These two asteroids have a redder spectral slope than any other D-type body, which are the reddest objects in the asteroid belt, and similar to RR and IR-class objects found in the outer Solar System among trans-Neptunian objects (TNOs) and Centaurs. Spectroscopic results suggest the presence of complex organic materials on the surface layer of these asteroids, implying that they could have formed in the vicinity of Neptune and been transplanted to the main belt region during a phase of planetary migration. 203 Pompeja is the only very red asteroid known so far among the ∼250 bodies with diameter larger than 110 km (i.e., presumably structurally intact) found in the asteroid belt. These discoveries provide more evidence that the main asteroid belt hosts a population of bodies that were formed in the outskirts of the Solar System.