2011 QF99
The asteroid 2011 QF99 is the first known Trojan horse of the planet Uranus. The discovery made in professional circles for a surprise, as was previously thought, it could be due to the gravitational influence of Jupiter and Neptune are no Uranus Trojans. However, the web is not unlimited time stable.
Discovery and designation
2011 QF99 was on 24 August 2011, two months after the first shot of the asteroid, as part of a larger sky survey for finding Transneptunischer objects and additional Neptune Trojans by a Canadian- French astronomer team led by Mike Alexandersen, Sarah Green Street and Brett Gladman (UBC ), John J. and Stephen DJ Gwyn Kavelaars ( NRCC ) and Jean -Marc Petit ( Observatoire de Besançon) with the Canada -France - Hawaii Telescope on Mauna Kea in Hawaii discovered. The first recording of the asteroid comes from the August 29, 2011, while the discovery was announced on 22 March 2013. The motion of the asteroid was detected by 3 shots with 5-minute exposure times.
Web properties
2011 QF99 orbits the sun on a prograde elliptical orbit between 2,353,023,800 km ( 15.729 AU) and 3,371,288,200 km ( 22.536 AU) distance from its center. The orbital eccentricity is 0.178, the orbit is tilted 10.806 degrees to the ecliptic. He moves within 10 ° to 170 ° of the orbit of Uranus, without coming too close to the planet there.
The orbital period of 2011 QF99 is 83.69 years or 30,566 days, 19 hours, 41 minutes and 22 seconds.
2011 QF99 is currently at the Lagrange point L4 of the Sun - Uranus system. In this position, he runs ahead of the Uranus by 60 °. This system forms a triangle whose side lengths currently 2.8 billion kilometers and are long to the sun between Uranus and 2011 QF99 3 million kilometers. It is believed that he is a former centaur, the front of at least 700,000 years, ie before - was a relatively short period of Uranus captured and forced to today's Trojan train - astronomically seen. The asteroid will be for at least another 70,000 years oscillate around the L4 point, and still at least another million years, yet share a co-orbital orbits with Uranus. During this time, three scenarios are possible: It is possible that 2011 QF99 will change during the period on the L5- point and thus a Uranus Trojans will remain. The other two variants provide a horseshoe or a quasi- satellite orbit before 2011 QF99 finally again becomes a centaur.
With Uranus Trojans train instabilities are generally expected and none of them is - in contrast to most of the known Jupiter Trojans, whose orbits are stable over billions of years - starting from a primodialen origin. Stable Trojans are possible in limited areas of the two Lagrangian points of Uranus, but in 2011 QF99 not in the stable region of the leading L4 point.
Computer simulation study indicates are at all times 0.4 % of the scattered population of the Centaurs within 6-34 Astronomical Units ( So the main influence of the three gas planet Saturn, Uranus and Neptune) co-orbital objects of Uranus. Of these, 64 % are horseshoe orbits describe 10% should be quasi-satellite and 26% of Uranus Trojans, evenly distributed between the L4 and L5 points of the Sun - Uranus system. The study also assumes that 2.8% of the Centaurs for the Neptune co-orbital. This gives a value of 3.2% Centaurs Trojan for both ice giants.
Physical Properties
The diameter of QF99 in 2011 is estimated at about 60 km, starting from an assumed albedo of 0.05. Probably it is similar to the shape of an asteroid, but may possibly of the same composition also produces a more comets. The Apparent magnitude of the asteroid is 22.6 mag. There are yet no spectral information.
Research
After its discovery in 2011 QF99 was dated back to photos until August 29, 2011, and so calculate its orbit. The asteroid was previously observed from 29 August 2011 to 21 October 2012, a total of 29 times so far, what an observation sheet of 419 days gave ( of Feb. 2014).