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2020-01-16 Abstract

Title: Some Interesting Co-orbital Motion in the Solar System
Speaker:  Martin Connors (Athabasca University Observatories)
Date: January 16 at 12:45
Location: R521, General Building II
Motion in the 1:1 mean motion resonance, often referred to as co-orbital motion, is ubiquitous in the Solar System, with many co-orbital companions known. Here we emphasize co-orbital motion about the Sun. The discovery of Jupiter Trojans over 100 years ago was slow to be recognized as a resonance. The co-orbital behavior found by Lagrange and mentioned in many introductory textbooks not only pre-dated concepts of resonance but was explicitly mentioned by Lagrange as likely not to exist. Other Trojan motion has been found, but notably, Saturn Trojans to not appear to exist. Even Earth has a Trojan asteroid, 2010 TK7, discovered by the WISE infrared mission but with orbital properties discovered by numerical simulation, orbital analysis, and follow-up ground-based observation. This body has an extreme orbit featuring “jumping” between Lagrange points, and no others have subsequently been found. Our continuing additions to the census of the Solar System’s small bodies has brought to light numerous retrograde objects. Naively one would expect such bodies, which if near in orbital space to a planet would encounter it twice per revolution, to be extremely unstable. Again a combination of simulation, orbit analysis, and observation established that a body in Jupiter’s orbital zone actually has such behavior: 2015 BZ509, now known as 514107 Kaʻepaokaʻawela. We await the return, and better observation, of another potential retrograde co-orbital of Jupiter, 2007 VW266, which has a high-inclination orbit. The Athabasca University Robotic Telescope, AURT, was initially developed for asteroid and comet discovery work, but never served in this role. Instead it has become a member of the Skynet network of robotic telescopes used mainly for education and rapid followup. The challenges of operating such a telescope in a subarctic climate zone will be described.
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