First Trojan companion of Uranus discovered using CFHT

Using the Canada-France-Hawaii Telescope's huge CCD camera "MegaCam", a Canada-France collaboration of astronomers have discovered the first known Trojan companion of the planet Uranus. The team [Mike Alexandersen, Sarah Greenstreet, and Brett Gladman from the University of British Columbia in Canada, astronomers JJ Kavelaars and Stephen Gwyn of Canada's National Research Council, and astronomer Jean-Marc Petit at the Observatoire de Besançon in France] has published the discovery, and numerical studies of the object's orbit and origin, in the August 30th, 2013 edition of Science magazine.

The Trojan, called 2011 QF99, was first identified by the team in CFHT observations from October 2011. With additonal CFHT observations between then and today, they confirmed the Trojan nature of the object. "This discovery was made possible because CFHT awards substantial amounts of time for the PhD thesis research of students like Alexandersen", said professor Brett Gladman, "and operates this excellent camera in a mode which makes this kind of astronomy possible."

Previously, Trojans were known to exist associated with Jupiter, Neptune, Mars, and Earth. The team has shown that 2011 QF99 shares the orbit of Uranus for hundreds of thousands of years into the future but, like some other Trojans of Neptune and Earth, will eventually leave this state and then be tossed around by the graviational pulls of the giant planets.

The motion of the uranian Trojan 2011 QF99. In this representation of the motion of 2011 QF99, one sees the motion over the next 59,000 years, looking down on the Solar System from above and turning at the same rate as the planet Uranus (which thus remains stationary at right). The Trojan osciallates forward and backwards, always keeping ahead of the planet.

For more information, and contact details, please see the University of British Columbia web page here.