Near-Infrared Color Properties of Kuiper Belt Objects and Centaurs: Final Results from the ESO Large Program
Résumé
We present near-IR JHK broadband photometry for 17 Kuiper Belt objects (KBOs) and Centaurs. The observations were performed within the ESO Large Program on the ``Physical Properties of Kuiper Belt Objects and Centaurs'' from 2001 January to 2002 August. We used the ISAAC instrument at the ESO 8 m Very Large Telescope. We compiled visible-near-IR colors for a total of 51 published objects and performed a statistical analysis. Color-color correlations show that the same coloring process is probably acting on Centaur and KBO surfaces in the visible-near-IR range. Centaurs with H-K smaller than the Sun (0.06) systematically display the reddest B-V colors (at the 2.5 sigma level). These Centaur surfaces are suspected of harboring material that has spectral signatures around 1.7-2.2 mum (water ice is a possibility; it was reported for the three objects that have published spectroscopy). We report no statistically significant evidence for a bimodal structure of the VJHK Centaur colors (Kolmogorov-Smirnov and dip tests on up to 17 objects). The Centaur H-K colors show some robust evidence (significance level >99.99%) for a continuous structure. We also report a statistically significant bimodal structure of the Centaur B-R distribution, which is compatible with the results published by Peixinho et al. in 2003 with different data. Classical KBOs show no trends at the 3 sigma level. The V-J color is marginally correlated with perihelion distance q (which is consistent with results reported by Doressoundiram et al. in 2005 on B-R colors). Resonant and scattered disk objects are underrepresented (seven and nine objects, respectively) and show no statistically significant trend. Some of the marginal trends are mentioned as worthy of subsequent monitoring.