Skip to comments.Stellar encounters as the origin of distant Solar System objects in highly eccentric orbits
Posted on 12/02/2004 4:51:41 PM PST by nicollo
If you can make sense of it, here's the article:
Stellar encounters as the origin of distant Solar System objects in highly eccentric orbits
SCOTT J. KENYON AND BENJAMIN C. BROMLEY
The Kuiper belt extends from the orbit of Neptune at 30 AU to an abrupt outer edge about 50 AU from the Sun. Beyond the edge is a sparse population of objects with large orbital eccentricities. Neptune shapes the dynamics of most Kuiper belt objects, but the recently discovered planet 2003 VB12 (Sedna) has an eccentric orbit with a perihelion distance of 70 AU, far beyond Neptune's gravitational influence. Although influences from passing stars could have created the Kuiper belt's outer edge and could have scattered objects into large, eccentric orbits, no model currently explains the properties of Sedna. Here we show that a passing star probably scattered Sedna from the Kuiper belt into its observed orbit. The likelihood that a planet at 6080 AU can be scattered into Sedna's orbit is about 50 per cent; this estimate depends critically on the geometry of the fly-by. Even more interesting is the 10 per cent chance that Sedna was captured from the outer disk of the passing star. Most captures have very high inclination orbits; detection of such objects would confirm the presence of extrasolar planets in our own Solar System.
Good article. Thanks.
Up until pretty recently, there were no all-sky surveys done of the Infrared sky (until the 80s or so). When the first antarctic telescopes opened up, and when the first infrared telescope flew in space, the very first project that was done was an all-sky survey...after all, what would be the point of building a telescope if you didn't know what interesting things you could see out there? You are almost guranteed to discover interesting new phoenomena (something that happened almost immediately with every other wavelength band).
So an object like Jupiter actually radiates more energy in the IR than it recieves from the Sun. I'd have to work through the math, but I am pretty sure that the all-sky surveys done with the Spitzer IR space telescope are good enough to see Jupiter in the IR out to about 1 light year or so (that's 60,000 AU). (Alpha Centauri is about 3.something light years out). The Oort clouds are believed to be much much closer, 1000 AU at most. The limit on something like a Uranus sized mass is a bit closer, around 10,000 AU or so, but the gravitational force by such a body falls pretty fast, so as to have much less of an effect. As such a body orbits the sun quite slowly, one wouldn't have to worry about missing it because it moved while you weren't looking for it.
So what does it matter that a planet is "alien" -- does that have any significance in its composition, or something?
Thanks, and I'll pass along the congrats from you and the others. Very kind.
Yes, it could have to do with Ox/Ix(Outer x/Inner x), my concept that Brian Marsden thought might be useful. Think of a solar version of galactic globular clusters : spinning, open spheres or lenticular shapes(2 of them)on slightly different solar radii/orbits. Every 26 million years they pass thru each other, throwing out a few comets, thus being partially responsible for the dinosaur-killer asteroid of 65 million years ago. A possible method of detection : a coded lasar pulse sent out into the ecliptic in a precise wavelength so as to excite known surface molecules on sedna/cometary bodies; basically a cosmic flashlight technique. If you get back an echo of a FAST moving body(at the center of the swarm)...
Thanks for explaining. Amazing stuff *bump*
They are probably all the same in God's eye, but you know, another star might have developed a different kind of life than our sun, and that life might, if it ever gets loose in the inner solar system, EAT US ALL.
Rogue Planet Find Makes Astronomers Ponder TheoryEighteen rogue planets that seem to have broken all the rules about being born from a central, controlling sun may force a rethink about how planets form, astronomers said on Thursday... "The formation of young, free-floating, planetary-mass objects like these is difficult to explain by our current models of how planets form," Zapatero-Osorio said... They are not linked to one another in an orbit, but do move together as a cluster, she said... Many stars in our own galaxy, the Milky Way, may have formed in a similar manner to the Orion stars, she said. So there could be similar, hard-to-see planets floating around free near the Solar System.
by Maggie Fox
October 5, 2000
It is laid-back fun to ponder what is out there in the Oort cloud. Usually the comets residing therein are pictured as a bunch of random dots, evenly distributed. That can't be the case as the T Tauri birth phase of the solar system 4.6 billion years ago was organized, not a random coalescence from the Mother Molecular birth cloud. To wit, the sun and planets are just a big saturn ring system wherein 99% of the mass goes into the central primary(of the original lenticular shape)but 99% of the cloud's original spin angular momentum goes into the orbiting planets and other minor debris(from the dust lane/accretion vortices by Bode's Law). Thus the comets, far from the sun, have the most SAM of the system, but as we look at galaxies and other assemblages in the universe, we see some kind of STRUCTURE, as in the primitive globular clusters orbiting the milky way. So, imagination time : just what is that overall STRUCTURE of trillions of comets in the Oort cloud out to 50,000 AU?
Out of This Solar System
By DENNIS OVERBYE
STRANGERS among us?
People who still haven't gotten over the idea that Antarctica is littered with meteorites from Mars now have an even more fantastical example of cosmic intermingling to contemplate. Thousands or even millions of planetoids from another star are probably lurking in the outer regions of our solar system, courtesy of a near collision between our Sun and the other star with their nascent planetary systems more than 4 billion years ago.
In a Nature paper this week a pair of astronomers, Scott Kenyon of the Harvard-Smithsonian Center for Astrophysics and Brian [BENJAMIN!] Bromley of the University of Utah, invoked such a world-swapping encounter as the best way to explain a strange world known as Sedna. Named for the Inuit goddess of the seas, Sedna travels in elongated orbit far beyond Pluto and the rest of the known solar system, never venturing closer than about seven billion miles from the Sun. It is the coldest, most distant object known to orbit the sun ....
The interest in these aliens goes beyond Sedna itself, however, to what they might tell scientists about the formation of our own solar system and others ....
Meant to ping you on this, if the others haven't already.
Retrograde satellites lose momentum to the parent body and slowly spiral inward, which puts an upper limit (possibly not considered by these researchers) on the length of time the retrograde moons have spent as satellites, and obviously, will spend as satellites.Did Jupiter Bully Other Planets in Sibling Rivalry?One possible explanation, discussed in Thursday's issue of the journal Nature, is that Uranus and Neptune formed much closer to the center of the action than their current positions might indicate. In this scheme, Jupiter and Saturn were bullies of a protoplanetary playground, shoving the other two future giants out of the way.
by Robert Roy Britt
8 December 1999Jupiter gave birth to Uranus and NeptuneNot too long ago, scientists regarded the orbits that the planets circle our Sun as being the ones they were born in. Now they are realising that this is not the case. Uranus and Neptune may have migrated outwards and Jupiter may have come in from the outer cold. Scientists have always been slightly puzzled by the positions of Uranus and Neptune because in their present locations it would have taken longer than the age of the Solar System for them to form. Scientists from Queen's University suggest that the four giant planets started out as rocky cores in the Jupiter-Saturn region, and that the cores of Uranus and Neptune were tossed out by Jupiter's and Saturn's gravity.
by Dr David Whitehouse
8 December, 1999Jupiter's Composition Throws Planet-formation Theories into DisarrayExamining four-year-old data, researchers have found significantly elevated levels of argon, krypton and xenon in Jupiter's atmosphere that may force a rethinking of theories about how the planet, and possibly the entire solar system, formed. Prevailing theories of planetary formation hold that the sun gathered itself together in the center of a pancake-shaped disk of gas and dust, then the planets begin to take shape by cleaning up the leftovers. In Jupiter's current orbit, 5 astronomical units from the sun, temperatures are too warm for the planetesimals to have trapped the noble gases. Only in the Kuiper belt -- a frigid region of the solar system more than 40 AU from the sun -- could planetesimals have trapped argon, krypton and xenon.
by Robert Roy Britt
Nov 17 1999
While lead researcher Tobias Owen does not put much stock in the idea that Jupiter might have migrated inward to its present position, other scientists on the team say the idea merits consideration. Owen expects the probes will find similarly high levels of noble gases in Saturn, Uranus and Neptune. Hints of these gases have even been found in the thick atmosphere of Venus, another planet now begging more study.Newfound Moons Tell Secrets of Solar SystemThe fact that most of the satellites' orbits are retrograde and eccentric speaks volumes about their origins: They had to have come from elsewhere, and been captured by the planets at some point. If they formed at the same time as the planets, from the spinning nebular disk, their orbits would be nearly circular and in the same direction as the planets' rotation, like the "regular" moons... In the case of the irregular satellites, they could not have shifted from an orbit around the Sun to an orbit around one of the giant planets without slowing down -- through friction in an atmosphere, perhaps; the influence of gravity; or a collision with another object... But there are two other possibilities for capture, Dr. Nesvorny said. One is that rapid growth of the core led to a corresponding increase in gravity, enough to pull down a nearby object. The other is that captured objects were a result of a collision between two planetesimals, the force of the collision being enough to dissipate the energy of at least one of them. Either of these two theories may be a more likely explanation for the satellites of Uranus and Neptune, which formed differently from Jupiter and Saturn, without the large amounts of gas.
by Henry Fountain
August 12, 2003
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What? They are allowing Velikovsky to publish in "Nature"? /sarc
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