2011 QF 99

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Asteroid
2011 QF 99
Properties of the orbit ( animation )
Orbit type Uranus Trojan (L 4 )
Major semi-axis 19.0252553  AU
eccentricity 0.1761159
Perihelion - aphelion 15.6746051 AU - 22.376 AU
Inclination of the orbit plane 10.83129 °
Sidereal period 82.98 ± 0.002 a
(30,310.46 ± 0.8 d )
Physical Properties
Medium diameter ~ 60 km
Albedo 0.05
Absolute brightness 9.6 to 9.7 mag
history
Explorer Mike Alexandersen
Sarah Greenstreet
Brett J. Gladman
John J. Kavelaars
Stephen DJ Gwyn
Jean-Marc Petit
Date of discovery October 24, 2011
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . The affiliation to an asteroid family is automatically determined from the AstDyS-2 database . Please also note the note on asteroid items.

The asteroid 2011 QF 99 is the first known Trojan horse from the planet Uranus . The discovery caused a surprise among experts, as it was previously assumed that no Uranus Trojans could exist due to the gravitational influence of Jupiter and Neptune. However, the orbit is not stable indefinitely.

Discovery and naming

2011 QF 99 was on 24 October 2011, two months after the first shot of the asteroid, as part of a larger sky survey for finding Transneptunischer objects and other Neptune -Trojaner by a Canadian - French astronomers to Mike Alexandersen, Sarah Green Street and Brett Gladman ( UBC ), John J. Kavelaars and Stephen DJ Gwyn ( NRCC ) and Jean-Marc Petit ( Observatoire de Besançon ) discovered with the Canada-France-Hawaii Telescope on Mauna Kea in Hawaii . The first image of the asteroid was taken on August 29, 2011, while the discovery was announced on March 22, 2013. The movement of the asteroid was recorded by taking 3 pictures with 5-minute exposure times.

Track properties

2011 QF 99 orbits the sun in a prograde , elliptical orbit between 2,353,023,800 km (15.729 AU ) and 3,371,288,200 km (22.536 AU) from its center. The orbit eccentricity is 0.178, the orbit is 10.806 ° inclined to the ecliptic . It moves within 10 ° to 170 ° of Uranus' orbit without getting too close to the planet.

The orbit period of 2011 QF 99 is 83.69 years.

2011 QF 99 is currently on the Lagrange point L 4 of the Sun-Uranus system. In this position it runs 60 ° ahead of Uranus. This system forms a triangle, the side lengths of which are currently 2.8 billion kilometers towards the sun and 3 million kilometers between Uranus and 2011 QF 99 . It is assumed that he is a former centaur who was captured by Uranus at least 700,000 years ago, i.e. a relatively short time ago - astronomically speaking - and forced onto today's Trojan orbit. The asteroid will oscillate around the L 4 point for at least another 70,000 years and will share an orbital orbit with Uranus for at least another million years . During this time, 3 scenarios are conceivable: It is possible that 2011 QF 99 will switch to the L 5 point during this time and thus remain a Uranus Trojan. The other two variants provide a horseshoe or a quasi-satellite orbit before QF 99 finally becomes a centaur again in 2011 .

In the case of Uranus Trojans, orbital instabilities are generally expected and none of them is assumed to have a primodial origin - in contrast to most known Jupiter Trojans, whose orbits have been stable for billions of years. Stable Trojans are possible in limited areas of the two Lagrange points of Uranus, but 2011 QF 99 is not in the stable region of the leading L 4 point.

According to a computer simulation study, 0.4% of the dispersed population of centaurs within 6 to 34 astronomical units (i.e. the main area of ​​influence of the three gas planets Saturn , Uranus and Neptune) are co-ordinate objects of Uranus. Of these, 64% are said to describe horseshoe orbits, 10% are said to be quasi-satellites and 26% Uranus Trojans, evenly distributed over the L 4 and L 5 points of the Sun-Uranus system. The study also assumes 2.8% of the centaurs for the Neptune co-ordinates. This gives a value of 3.2% Centaur Trojans for both ice giants .

Physical Properties

The diameter of 2011 QF 99 is estimated to be around 60 kilometers based on an assumed albedo of 0.05. It probably resembles the shape of an asteroid, but its composition may also look more like a comet . The apparent magnitude of the asteroid is 22.6 mag. So far there is no spectral information.

exploration

After its discovery in 2011, QF 99 could be found on older images back to November 2, 2008, and thus its orbit was calculated. The last documented observation of the asteroid took place on December 18, 2018. It was observed a total of 84 times, which corresponds to an observation sheet of 3698 days (as of Aug. 2019).

See also

Web links

Individual evidence

  1. ↑ UBC researchers unveil Uranus' first known Trojan companion ( Memento from February 28, 2014 in the Internet Archive ) (August 29, 2013)
  2. ↑ A Uranian Trojan and the frequency of temporary giant-planet co-orbitals (March 22, 2013)
  3. ↑ 2011 QF 99 at JPL