2004 XR190

Encyclopedia : 2 : 20 : 200 : 2004 XR190

**2004 XR₁₉₀**
Orbital elements
Eccentricity (orbit)>e
Inclination>i	°
Perihelion>q	AU
Argument of perihelion>ω	°
Semi-major axis>a	AU
Longitude of the ascending node>ω	°
Aphelion>Q	AU
Mean anomaly>M	°
Orbital period>P	years
Mean motion>n	°/day
Time of perihelion passage>TP

|}} 2004 XR₁₉₀ (also written 2004 XR190) is a newly discovered trans-Neptunian object located in the scattered disc. Astronomers led by Lynne Allen of the University of British Columbia made the discovery as part of the Legacy Survey using the Canada-France-Hawaii Telescope (CFHT). The discovery team has temporarily nicknamed the object "Buffy", after the fictional vampire slayer, and proposed a different official name to the IAU.

2004 XR₁₉₀ is particularly unusual for two reasons. With an inclination of 47 degrees, it is the most "tilted" object discovered thus far, traveling further "up and down" than "left to right" around the Sun when viewed edge-on along the ecliptic. Second, it has an unusually circular orbit for a scattered disc object. While it has been hypothesized that Scattered Disc Objects (SDOs) have been ejected into their current orbits by gravitational interactions with Neptune, the low eccentricity of its orbit and the length of its perihelion (SDOs generally have highly eccentric orbits and perihelions less than 38 AU) seems hard to reconcile with such celestial mechanics. This has led to some uncertainty as to the current theoretical understanding of the outer Solar System.

The object has a diameter estimated at 500 to 1000 kilometres, between a quarter and half the size of Pluto, and orbits between 52 and 62 AU (7.8 and 9.3 Tm) from the Sun.

Image:XR190orb_top.gif|The orbit of Buffy (also known as object 2004 XR₁₉₀). The ring in the center is Earth's orbit shown for scale. Units are in AUs.

Image:XR190orb_side.gif|A side view of 2004 XR₁₉₀'s orbit, showing the object's high inclination. Units are AUs.

External links

[MPEC circular detailing discovery]
[Discovery webpage by research team]
[Canada-France-Hawaii Telescope Legacy Survey]
Discovery paper

Large trans-Neptunian objects[http://encycl.opentopia.com/ edit ]

Kuiper belt: Pluto (Charon) | Orcus | Ixion | 2002 UX₂₅ | Varuna | 2002 TX₃₀₀ | 2003 EL₆₁ | Quaoar | 2005 FY₉ | 2002 AW₁₉₇

Scattered disc: 2002 TC₃₀₂ | 2003 UB₃₁₃ | 2004 XR₁₉₀ | Sedna†

See also Triton, astronomical objects and the solar system's list of objects, sorted by radius or mass.
For pronunciation, see: Centaur and TNO pronunciation.
† Current MPC classification. Some consider Sedna an Oort cloud object.

The minor planets
Vulcanoids \| Near-Earth asteroids \| Main belt \| Jupiter Trojans \| Centaurs \| Damocloids \| Comets \| Trans-Neptunians (Kuiper belt · Scattered disc · Oort cloud)
For other objects and regions, see: , , asteroid moons and the Solar system For a complete listing, see: List of asteroids. See also Pronunciation of asteroid names and Meanings of asteroid names.

[http://encycl.opentopia.com/ edit ] The Solar System

Planets: Mercury (planet)>Mercury - Venus - Earth - Mars - Jupiter - Saturn - Uranus - Neptune - Pluto
Other: Sun - Moon>The Moon - Asteroid belt - Main-belt comets - Kuiper belt - Scattered disc - Oort cloud
See also astronomical objects and the solar system's list of objects, sorted by radius or mass.

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