Clues to the origin of Jupiter’s Trojans: the libration amplitude distribution F. Marzari, P. Tricarico, and H. Scholl Katie McGleam TERPS conference Dec. 7, 2004

Outline Background Background Trojan origin: Trojan origin: Mutual Collisions Mutual Collisions Mass Growth of Jupiter Mass Growth of Jupiter Combination Combination Dynamical Instability Dynamical Instability Put it all together! Put it all together!

Trojans orbit at the stable L4 and L5 points of Jupiter. Trojans orbit at the stable L4 and L5 points of Jupiter. Estimated that there are about half as many Trojans as main belt asteroids. (Shoemaker et al, 1989) Estimated that there are about half as many Trojans as main belt asteroids. (Shoemaker et al, 1989) Libration amplitudes Libration amplitudes Minor Planet Center Plot prepared on 1997 March 7 Background

Capture: Mutual Collisions Model: Model: Sun, Jupiter, Saturn 5000 planetesimals a: 4.9 – 5.5 AU, e: 0.0 – 0.1, i: 0-1.5° Jupiter & Saturn: fixed mass of 10 M  Results: Results: 450 captured, 54 with D < 40°

Capture: Mass Growth of Jupiter Model: Model: same as before, except: Jupiter and Saturn grow at the same rate from 10 M  to their present sizes over 2x10 4 years. no collisions Results: Results: 1850 captured, all with D > 40°, most would be unstable

Mutual Collisions + Mass Growth Model: Model: Two stages: 1. Collisions only, 2x10 4 years, Jupiter & Saturn: fixed mass of 10 M  2. Mass growth over another 2x10 4 years, with collisions Results: Results: 346 captured, 67 with D < 40° Shaded region: captured before mass growth

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