"Because of its odd orbital features, when it comes to testing ideas about how the solar system formed, this new object may become known as Buffy the Theory Slayer."

Planet Buffy: information on the new Kuiper Belt planetoid

A new planetoid with unique properties has been discovered beyond the orbit of Neptune; it has been given the preliminary name "Buffy." It was discovered by the Canada-France-Hawaii Telescope (CFHT), a non-profit organization that operates a world class 3.6 meter telescope atop Mauna Kea, a dormant Hawaiian volcano rising 4,200 meters above the Pacific ocean. 

2004 XR190 Wikipedia

"004 XR190 (also written 2004 XR190) is a 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."

"Buffy" challenges theories of how solar system was formed

"ASTRONOMERS have discovered an object half the size of Pluto orbiting the Sun beyond Neptune which they say is threatening to rewrite theories about how the solar system was formed. The body, which has been nicknamed Buffy, has an almost circular orbit which has baffled scientists as most objects in this area, known as the Kuiper Belt, have "highly eccentric" orbits. The orbit is difficult to explain using previous theories about the solar system's formation and has prompted a rethink. Buffy was discovered by the Canada-France-Hawaii Telescope in 2004, but it was not until October this year that it started to become clear that it was something strange. A statement by the Canada-France Ecliptic Plane Survey said: "Measurement of Buffy's new position confirmed that Buffy was unlike any other previously-known object because it was on a nearly circular orbit while at a very large distance."

Space researchers attempt to explain 'Buffy's' features

"COULD the outer solar system harbor planetary samples nabbed from a passing star? That's a question some astronomers are asking as they try to explain "Buffy," a recently discovered, frigid mini-planet 300 to 600 miles across. It orbits the sun just beyond the edge of the Kuiper Belt, a broad swath of icy objects that extends far beyond Neptune. Because of its odd orbital features, when it comes to testing ideas about how the solar system formed, this new object may become known as Buffy the Theory Slayer.

The object "is a challenge to theories of the evolution of the solar system," acknowledges Lynne Allen, a postdoctoral fellow at the University of British Columbia in Vancouver who discovered Buffy. "It points out that a lot more went on than we think" as planets, particularly the gas giants, formed and wandered to their current locations around the sun. Dr. Allen is part of a team using the Canada-France-Hawaii Telescope on Hawaii's Mauna Kea to conduct a survey of the Kuiper Belt. The team announced the discovery last week, a year after Allen spotted the object as she was processing the survey data. During the interim, astronomers at the Kitt Peak National Observatories outside Tucson, Ariz., and the Mt. Palomar Observatory near San Diego conducted additional observations that helped pin down Buffy's orbital characteristics. Buffy orbits the sun once every 440 years. Buffy orbits the sun once every 440 years at a distance ranging from 52 to 62 astronomical units from the sun (one AU is 93 million miles).

Buffy's arresting traits begin with its nearly circular orbit. Those of its nearest neighbors are more elliptical. More puzzling, Buffy's orbit is severely tilted compared with those of planets, comets, and Kuiper Belt objects -- some 47 degrees off kilter from the rest of the solar system. It's a feature that defies all but the most convoluted explanations for how the solar system achieved its current structure, some astronomers say. Enter Scott Kenyon and Benjamin Bromley, two researchers who model solar-system evolution on high-powered computers. Dr. Kenyon, a senior scientist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., explains that the sun probably was born as part of a cluster of stars whose combined gravity bound members only loosely to the group.

Thus, over the 4 billion years since the sun formed, the clutch of suns would have scattered. One escapee could have dropped off samples of its planetary building blocks -- perhaps Buffy -- in the outer reaches of our solar system as it headed off on its own spin about the galaxy. Kenyon and Dr. Bromley, a planetary scientist at the University of Utah, were running computer simulations to see if an encounter with another cluster member early in the sun's history might have given Sedna, another object beyond the Kuiper Belt, its highly inclined, extremely elliptical orbit. The two calculated that if another star passed close enough to the sun and with the right trajectory, there was at least a 50 percent chance that it could have tugged Sedna out of the Kuiper Belt and into its current orbit. But as the two reviewed their calculations, they also found that there was a 10 percent chance that the two stars actually could have swapped material from the extended disks of planetary building blocks that surrounded each of them. Depending on conditions, the sun could have captured up to one-third of the objects orbiting the passing star at distances of from 60 to 80 AU.

In a paper the two published last year in the journal Nature, they concluded that finding objects beyond the Kuiper Belt with orbital tilts larger than 40 degrees could confirm the existence of "extrasolar planets" in our solar system's own backyard.

Now, with Buffy representing the third highly inclined orbital oddball discovered over the past few years, "maybe this idea we had isn't completely out to lunch," Kenyon says.

To be sure, no theory at the moment, including his and Bromley's, "makes enough predictions for finding the distinctive features that would point to one" as the correct explanation, he says.

But he adds that the stellar-flyby is the most straightforward explanation to date. He and his colleague would like to run the model again to see if it yields estimates of the number of these objects astronomers could expect to find."

Discovery of "Buffy", a large Kuiper Belt object with an unusual orbit

"A TEAM of astronomers working in Canada, France and the United States have discovered an unusual small body orbiting the Sun beyond Neptune, in the region astronomers call the Kuiper belt. This new object is twice as far from the Sun as Neptune and is roughly half the size of Pluto. The body, temporarily code-named "Buffy", has a highly unusual orbit which is difficult to explain using previous theories of the formation of the outer Solar System.

Currently 58 astronomical units from the Sun (1 astronomical unit, or AU, is the distance between the Earth and the Sun), the new object never approaches closer than 50 AU, because its orbit is close to circular. Almost all Kuiper belt objects discovered beyond Neptune are between 30 AU and 50 AU away. Beyond 50 AU, the main Kuiper belt appears to end, and what few objects have been discovered beyond this distance have all been on very high eccentricity (non-circular) orbits.

Most of these high-eccentricity orbits are the result of Neptune "flinging" the object outward by a gravitational slingshot. However, because this new object does not approach closer than 50 AU, a different theory is needed to explain its orbit. Complicating the problem, the object's orbit also has an extreme tilt, being inclined (tilted) at 47 degrees to the rest of the Solar System."

Discovery of a large Kuiper Belt object with an unusual orbit

Oddball object circles sun beyond Neptune

"A DISTANT OBJECT named Buffy has been spotted circling the sun far beyond Neptune in a strange tilted orbit that is making some astronomers question how the outer reaches of the solar system formed. Officially called 2004 XR 190 by the International Astronomical Union but code-named Buffy, the object is now about 58 times as far from the sun as Earth, and twice as far from the sun as Neptune. At this distance from the heart of the planetary system, Buffy is a considered a Kuiper Belt object, but an odd one, astronomers working in Canada, France and the United States said in a statement on Tuesday. The Kuiper Belt is a ring of space objects that may be remnants from the early solar system. Most of these objects orbit the sun between 30 and 50 times the distance that Earth orbits. The distance from Earth to the sun -- 93 million miles -- is known as one astronomical unit. Most Kuiper Belt objects are contained in this thick swath of space, and most have elliptical orbits, which means they get much closer to Neptune during parts of their orbits. They generally orbit in the same plane as most of the planets and other solar system objects. But Buffy's circular track means it stays beyond the 50 astronomical unit range for its entire orbit, never getting much closer than 52 astronomical units, or AU, and sometimes swinging out to 62 AU. The only other known object that never gets within the 50 AU boundary is Sedna, which flings out to 900 AU and swoops in to 76 AU. But Sedna's orbit is typically elliptical, while Buffy goes around in a near-perfect circle. And Buffy's orbit is tilted at a 47 degree angle from the rest of the solar system. The highly eccentric orbits of the other Kuiper Belt objects are thought to be the result of being flung outward in a slingshot effect by Neptune's gravity. But Buffy's orbit does not follow that pattern."

Mini-world called Buffy sends science spinning: What's way out there? Moons and ice dwarfs, too

"WE'RE TALKING WAY FAR AWAY -- objects orbiting at distances more than 3 billion miles from the sun. That's about where Pluto, the ninth planet, orbits. The largest and most distant of the ice dwarfs is nicknamed Xena after the television warrior princess. Discovered in 2003, it's 1,600 miles across and 20% bigger than Pluto. Xena has a moon of its own, named Gabrielle after Xena's sidekick on television. One of the smaller Kuiper Belt mini-worlds is nicknamed Santa and has a moon named Rudolph. Until the International Astronomical Union assigns them official names, the other sizable mini-worlds are known as Easter Bunny, Orcus, Quaoar, Ixion and Buffy. The most distant such object is called Sedna; its elliptical orbit carries it more than 9 billion miles beyond the sun."


The solar system isn't what it used to be

"THE FAMILIAR SOLAR SYSTEM that you learned about in school - nine well-behaved planets, from Mercury to Pluto, circling sedately in tidy paths around the sun - isn't what it used to be. Astronomers recently have discovered a flock of at least eight other planetlike objects in far-out, sometimes wildly eccentric orbits. Four new "ice dwarfs," plus two more probable moons around Pluto, were announced publicly in the last six months. The latest mini-world, temporarily nicknamed "Buffy" and located more than 5 billion miles from the sun, was announced on Dec. 13. The object, about half the size of Pluto, was spotted roaming through the so-called Kuiper Belt, a vast junkyard of icy, rocky bodies stretching for billions of miles beyond the orbit of Neptune. The first scientific mission to explore Pluto and the Kuiper Belt, a nine-year voyage to the outer solar system, is scheduled to be launched in January. "Next month we set sail for Pluto," Alan Stern, the project's chief scientist at the Southwest Research Institute in Boulder, Colo., exulted. Unlike the rest of the planetary family, Pluto resides in the Kuiper Belt. But it's not alone there. More than 1,000 frozen chunks of debris left over from the formation of the solar system have been found since 1992. Astronomers expect that there are at least half a million more pieces out there. "The discovery of the Kuiper Belt in the 1990s has given Pluto a place to call home, with icy brethren to call its own," Neil deGrasse Tyson, the director of the Hayden Planetarium at the American Museum of Natural History in New York, said in an e-mail message. "The Kuiper Belt is the largest structure in the solar system," Stern said Monday. "We used to think Pluto was a misfit," but now Earth and the other inner planets are the oddballs. Even the inner solar system doesn't look the way it used to. Astronomers no longer think that the four biggest planets have always been spinning along in their present locations. Instead, they now say, Jupiter has moved toward the sun from its original home, while Saturn, Uranus and Neptune all have slid outward from their birthplaces, according to Donald Yeomans, a planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif."





since 1 August 2007