Albedos of Small Jovian Trojans

Abstract

We present thermal observations of 44 Jovian Trojan asteroids with diameters (D) ranging from 5 to 24 km. All objects were observed at a wavelength of 24 microns with the Spitzer Space Telescope. Measurements of the thermal emission and of scattered optical light, mostly from the University of Hawaii 2.2-meter telescope, together allow us to constrain the diameter and geometric albedo of each body. We find that the median R-band albedo of these small Jovian Trojans is about 0.12, much higher than that of "large" Trojans with D > 57 km (0.04). Also the range of albedos among the small Trojans is wider. We attribute the Trojan albedos to an evolutionary effect: the small Trojans are more likely to be collisional fragments and so their surfaces would be younger. A younger surface means less cumulative exposure to the space environment, which suggests that their surfaces would not be as dark as those of the large, primordial Trojans. In support of this hypothesis is a statistically significant correlation of higher albedo with smaller diameter in our sample alone and in a sample that includes the larger Trojans.

41 pages, 6 figures, 4 tables, AASTeX

References in corpus (8)

• Analytical protostellar disk models 1: the effect of internal dissipation and surface irradiation on the structure of disks and the location of the snow line around Sun-like stars
• Thermal inertia of near-Earth asteroids and implications for the magnitude of the Yarkovsky effect
• Visible spectroscopic and photometric survey of Jupiter Trojans: final results on dynamical families
• The Properties of Jovian Trojan Asteroids Listed in SDSS Moving Object Catalog 3
• Taxonomy of asteroid families among the Jupiter Trojans: Comparison between spectroscopic data and the Sloan Digital Sky Survey colors
• Fraction of Contact Binary Trojan Asteroids
• Comet 162P/Siding Spring: A Surprisingly Large Nucleus
• Dynamics of Jupiter Trojans during the 2:1 mean motion resonance crossing of Jupiter and Saturn

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