After 8 years of observations scientists from the SETI Institute have found an exotic orbit for the largest Trojan asteroid, (624) Hektor—the only one known to possess a moon. The formation of this system made of a dual primary and a small moon is still a mystery, but they found the asteroid could be a captured Kuiper body product of the reshuffling of giant planets in our solar system. The results are being published today in Astrophysical Journal Letters.
This study, based on W. M. Keck Observatory data and photometric observations from telescopes throughout the world, suggests that the asteroid and its moon are products of the collision of two icy asteroids. This work sheds light on the complex youth of our solar system, when the building blocks that formed the core of giant planets and their satellites were tossed around or captured during the giant planet migrations.
In 2006, a small team of astronomers led by Franck Marchis, astronomer at the Carl Sagan center of the SETI Institute, detected the presence of a small 12 km diameter moon around the large Trojan asteroid (624) Hektor. They used the 10 m Keck II telescope atop Mauna Kea, fitted with the NIRC-2 (the Near-Infrared Camera 2) instrument behind the adaptive optics and laser guide star system (LGS-AO).