Population and Size Distribution of Small Jovian Trojan Asteroids

We present a study of Jovian Trojan objects detected serendipitously during the course of a sky survey conducted at the University of Hawaii 2.2 m telescope. We used a 8192 × 8192 pixel charge-coupled device (CCD) mosaic to observe 20 deg2 at locations spread over the L4 Lagrangian swarm and reached a limiting magnitude V = 22.5 (50% of maximum detection efficiency). Ninety-three Jovian Trojans were detected with radii 2 km ≤ r ≤ 20 km (assumed visual albedo 0.04). Their differential magnitude distribution has a slope of 0.40 ± 0.05, corresponding to a power-law size distribution index 3.0 ± 0.3 (1 σ). The total number of L4 Trojans with radii ≥1 km is of order 1.6 × 105, and their combined mass (dominated by the largest objects) is ~10-4 MEarth. The bias-corrected mean inclination is 137 ± 05. We also discuss the size and spatial distribution of the L4 swarm.

[1]  S. Peale.  The Effect of the Nebula on the Trojan Precursors , 1993 .

[2]  D. Cruikshank.  Radii and Albedos of four Trojan asteroids and Jovian satellites 6 and 7 , 1977 .

[3]  David Jewitt,et al.  A Semiautomated Sky Survey for Slow-moving Objects Suitable for a Pluto Express Mission Encounter , 1998 .

[4]  C. Trujillo,et al.  Large Kuiper Belt Objects: The Mauna Kea 8K CCD Survey , 1998 .

[5]  S. Tremaine,et al.  A Search for Slow-Moving Objects and the Luminosity Function of the Kuiper Belt , 1995 .

[6]  A. Nakamura,et al.  Velocity distribution of fragments formed in a simulated collisional disruption , 1991 .

[7]  Julio A. Fernández.  Dynamical capture and physical decay of short-period comets , 1985 .

[8]  T. Owen,et al.  Near-Infrared Spectroscopy of Low-Albedo Surfaces of the Solar System: Search for the Spectral Signature of Dark Material , 1998 .

[9]  David Jewitt,et al.  CCD spectra of asteroids. II - The Trojans as spectral analogs of cometary nuclei , 1990 .

[10]  Richard P. Binzel,et al.  Trojan, Hilda, and Cybele asteroids: New lightcurve observations and analysis , 1992 .

[11]  Arlo U. Landolt,et al.  UBVRI Photometric Standard Stars in the Magnitude Range 11 , 1992 .

[12]  M. Davidson,et al.  Earth, Moon and Planets , 1947, Nature.

[13]  Jack Wisdom,et al.  Dynamical Stability in the Outer Solar System and the Delivery of Short Period Comets , 1993 .

[14]  E. Cloutis,et al.  Near-Infrared Spectroscopy of Primitive Solar System Objects , 1994 .

[15]  E. Shoemaker,et al.  Dynamical evolution of Jupiter's Trojan asteroids , 1997, Nature.

[16]  J. S. Dohnanyi.  Collisional model of asteroids and their debris , 1969 .

[17]  Francesco Marzari,et al.  Collisional Evolution of Trojan Asteroids , 1997 .

[18]  P. Farinella,et al.  Collision Rates and Impact Velocities in the Trojan Asteroid Swarms , 1996 .