Trojans i Hildas de baix i alt albedo: un origen similar o diferent?

2010-10-14

00:00

Facultat de Ciències, Torre C5, Campus UAB - Bellaterra - Barcelona

Jupiter Trojans and Hilda asteroids are small primitive bodies located near or beyond the snow line, around respectively the L4 and L5 Lagrange points of Jupiter at 5.2 AU from the sun (Trojans) and in the 2:3 mean-motion resonance with Jupiter near 3.9 AU (Hildas).

Our current understanding of the early dynamical evolution of the Solar System tells us that they probably originated from the primordial transneptunian region from which they were captured in their current location (Nice model; Morbidelli et al. 2005; Levison et al. 2009). In addition, this region not only comprised planetesimals formed beyond the snow line (D-, T- and X-type asteroids) but also a minor population of rocky interlopers (e.g., A-, S-, V type asteroids) that migrated outward during the very early evolutionary phases of the Solar System 5 to 7 My after its formation (Grand Tack model; Walsh et al. 2011).

The recent discovery by WISE (Grav et al. 2011; 2012a; 2012b) and Spitzer (Fernandez et al. 2009) of high albedo (pv~0.15) asteroids within jovian Trojans and Hildas opened the possibility of an observational evidence for the presence of a small fraction (~2 %) of such interlopers among these two low albedo (pv~0.07) populations.

I will present the first spectroscopic characterization of a sample of high albedo Trojans and Hildas obtained with X-SHOOTER and SpeX in the visible and/or near-infrared ranges. This study allowed us to investigate the origin of these high albedo objects and to provide an estimate of the contamination rate of jovian Trojans and Hilda asteroids by objects that do not belong to the C-/T-/D-type complex (e.g., A-, S-, V-type asteroids), thus constraining migration models.

Contact email: mmarsset(a)eso.org [NOT TRANSLATED]