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In planetary astronomy, a centaur is a small Solar System body that orbits the Sun between Jupiter and Neptune and crosses the orbits of one or more of the giant planets. Centaurs generally have unstable orbits because they cross or have crossed the orbits of the giant planets; almost all their orbits have dynamic lifetimes of only a few million years, but there is one known centaur, 514107 Kaʻepaokaʻawela, which may be in a stable orbit. Centaurs typically exhibit the characteristics of both asteroids and comets. They are named after the mythological centaurs that were a mixture of horse and human. Observational bias toward large objects makes determination of the total centaur population difficult. Estimates for the number of centaurs in the Solar System more than 1 km in diameter range from as low as 44,000 to more than 10,000,000.
A quasi-satellite is an object in a specific type of co-orbital configuration with a planet where the object stays close to that planet over many orbital periods.
The Panoramic Survey Telescope and Rapid Response System located at Haleakala Observatory, Hawaii, US, consists of astronomical cameras, telescopes and a computing facility that is surveying the sky for moving or variable objects on a continual basis, and also producing accurate astrometry and photometry of already-detected objects. In January 2019 the second Pan-STARRS data release was announced. At 1.6 petabytes, it is the largest volume of astronomical data ever released.
In astronomy, a trojan is a small celestial body (mostly asteroids) that shares the orbit of a larger body, remaining in a stable orbit approximately 60° ahead of or behind the main body near one of its Lagrangian points L4 and L5. Trojans can share the orbits of planets or of large moons.
In astronomy, a co-orbital configuration is a configuration of two or more astronomical objects orbiting at the same, or very similar, distance from their primary; i.e., they are in a 1:1 mean-motion resonance..
474640 Alicanto (provisional designation 2004 VN112) is a detached extreme trans-Neptunian object. It was discovered on 6 November 2004, by American astronomer Andrew C. Becker at Cerro Tololo Inter-American Observatory in Chile. It never gets closer than 47 AU from the Sun (near the outer edge of the main Kuiper belt) and averages more than 300 AU from the Sun. Its large eccentricity strongly suggests that it was gravitationally scattered onto its current orbit. Because it is, like all detached objects, outside the current gravitational influence of Neptune, how it came to have this orbit cannot yet be explained. It was named after Alicanto, a nocturnal bird in Chilean mythology.
83982 Crantor (provisional designation 2002 GO9) is a centaur in a 1:1 resonance with Uranus, approximately 60 kilometers (37 miles) in diameter. It was discovered on 12 April 2002, by astronomers of the Near-Earth Asteroid Tracking at the Palomar Observatory in California, United States. This minor planet was named for Crantor from Greek mythology.
54509 YORP (provisional designation 2000 PH5) is an Earth co-orbital asteroid discovered on 3 August 2000 by the Lincoln Laboratory Near-Earth Asteroid Research (LINEAR) Team at Lincoln Laboratory Experimental Test Site in Socorro, New Mexico. Measurements of the rotation rate of this object provided the first observational evidence of the YORP effect, hence the name of the asteroid. The asteroid's rate of rotation is increasing at the rate of (2.0 ± 0.2) × 10−4 deg/day2 which between 2001 and 2005 caused the asteroid to rotate about 250° further than its spin rate in 2001 would have predicted. Simulations of the asteroid suggest that it may reach a rotation period of ~20 seconds near the end of its expected lifetime, which has a 75% probability of happening within the next 35 million years. The simulations also ruled out the possibility that close encounters with the Earth have been the cause of the increased spin rate.
Detached objects are a dynamical class of minor planets in the outer reaches of the Solar System and belong to the broader family of trans-Neptunian objects (TNOs). These objects have orbits whose points of closest approach to the Sun (perihelion) are sufficiently distant from the gravitational influence of Neptune that they are only moderately affected by Neptune and the other known planets: This makes them appear to be "detached" from the rest of the Solar System, except for their attraction to the Sun.
2010 EU65 is a centaur, approximately 64 kilometers (40 miles) in diameter, orbiting the Sun in the outer Solar System. The object is also a promising Uranus horseshoe librator candidate. It was first observed on 13 March 2010, by American astronomers David Rabinowitz and Suzanne Tourtellotte, observing from Cerro Tololo and La Silla Observatory in Chile. As of 2021, it has neither been numbered nor named.
2011 SL25, also written as 2011 SL25, is an asteroid and Mars trojan candidate that shares the orbit of the planet Mars at its L5 point.
(687170) 2011 QF99 is a minor planet from the outer Solar System and the first known Uranus trojan to be discovered. It measures approximately 60 kilometers (37 miles) in diameter, assuming an albedo of 0.05. It was first observed 29 August 2011 during a deep survey of trans-Neptunian objects conducted with the Canada–France–Hawaii Telescope, but its identification as Uranian trojan was not announced until 2013.
2013 BS45 (also written 2013 BS45) is a horseshoe companion to the Earth like 3753 Cruithne. Like Cruithne, it does not orbit the Earth in the normal sense and at times it is on the other side of the Sun, yet it still periodically comes nearer to the Earth in sort of halo orbit before again drifting away. While not a traditional natural satellite, it does not quite have normal heliocentric orbit either and these are sometimes called quasi-satellties or horseshoe orbits.
2013 RF98 is a trans-Neptunian object. It was discovered on September 12, 2013, at Cerro Tololo-DECam.
(636872) 2014 YX49 (provisional designation 2014 YX49) is a centaur and Uranus co-orbital, approximately 77 kilometers (48 miles) in diameter, first observed on December 26, 2014, by the Pan-STARRS survey. It is the second known centaur on a tadpole orbit with Uranus, and the fourth Uranus co-orbital discovered after 83982 Crantor, 2011 QF99 and (472651) 2015 DB216.
2009 SE is a small asteroid and Mars trojan orbiting near the L5 point of Mars (60 degrees behind Mars on its orbit).
2018 EC4 is a small asteroid and Mars trojan orbiting near the L5 point of Mars (60 degrees behind Mars on its orbit).
2011 SP189 is a small asteroid and Mars trojan orbiting near the L5 point of Mars (60 degrees behind Mars on its orbit).
2020 PN1 is a sub-kilometer asteroid, classified as a near-Earth object of the Aten group, that is a temporary horseshoe companion to the Earth. There are dozens of known Earth horseshoe librators, some of which switch periodically between the quasi-satellite and the horseshoe co-orbital states.
A Uranus trojan is an asteroid that shares an orbit with Uranus and the Sun. Predicted in simulations earlier, two trojans have been discovered in Uranus’s Lagrangian point L4 (leading Uranus).
References
- ↑ "2015 DB216 – Minor Planet Center". Minor Planet Center. International Astronomical Union . Retrieved 18 March 2015.
- 1 2 "JPL Small Body Database Browser". JPL (2015-04-23 last obs.). NASA . Retrieved 4 April 2016.
- ↑ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (15 May 2017). "Asteroid 2014 YX49: a large transient Trojan of Uranus". Monthly Notices of the Royal Astronomical Society. 467 (2): 1561–1568. arXiv: 1701.05541 . Bibcode:2017MNRAS.467.1561D. doi: 10.1093/mnras/stx197 .
- ↑ de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (27 July 2015). "Asteroid 2015 DB216: a recurring co-orbital companion to Uranus". Monthly Notices of the Royal Astronomical Society. 453 (2): 1288–1296. arXiv: 1507.07449 . Bibcode:2015MNRAS.453.1288D. doi: 10.1093/mnras/stv1725 .
