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General >> Discussion >> Were Triton and 2003 UB313 once part of a binary?
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Message started by Michael_C._Emmert on 10/17/05 at 19:45:00

Title: Were Triton and 2003 UB313 once part of a binary?
Post by Michael_C._Emmert on 10/17/05 at 19:45:00

Howdy, folks  :)

I'd like to show you all my simulation for an explanation of how Triton got into it's strange, backwards orbit around Neptune.

This has puzzled astronomers for some time.  Triton could not have formed from the same nebula as Neptune and have wound up in a retrograde orbit.  It must be a captured body.

But how?  When an object approaches another object from an infinite distance, their gravitational pull always keeps them above escape velocity.  Somthing must slow the bodies down in order for a capture to take place, something like a rocket firing, a collision, or transfer of energy to a third object.

I have modeled such scenarios on GravitySimulator:

http://orbitsimulator.com/gravity/simulations/XGorilla%201.1.gsim

The simulation starts with a binary pair, codenamed Vicki and Sandra, in front of Neptune in it's orbit around the Sun.  The base simulation used was planetsonly, part of the GravitySimulator package.  I copied Uranus' moons  onto Neptune and changed their names slightly to Aerial, Umbilical, Titanium, and Obermensch.   (I used Vicki and Sandra rather than Xena and Triton for the binaries' names because half the time Xena wound up in orbit and Triton was flung into the outer solar system. ::))

I made a bunch of these.  I have submitted this one because so far, it seems the most realisitic one.  Sandra winds up in an elliptical orbit 352,000 km x 5,900,000 km.  (Triton's orbital altitude above Neptune is 355,000 km).  Such an orbit, being retrograde, would decay and come closer to Neptune.  A retrograde orbit has a different effect that a prograde orbit; the objects approach each other over time, rather than receding as Earth's moon is doing.

Later simulations will start with the binary coming into the plane of the ecliptic at an angle.  The posted simulation involves a polar pass, which is pretty likely.  I think this binary formed in the Sun/Neptune Lagrange point L4 or L5, and that the binary escaped the Lagrange stability zone perpendicular to the plane of the ecliptic.  I am modeling clusters of objects in the Lagrange points, but I think I need to do a few more to make the most realistic model.  So far, it seems that an object can move up to half a billion kilometers above and below the plane of the ecliptic and still be trapped in the 1:1 Lagrange resonance for Neptune and the Sun.

I would like to comment on the likelyhood of a collision between Triton and an original moon of Neptune.  One of my simulations was done in the ecliptic plane, and I decided to leave the moon (Vicki, in that case) orbiting in it's retrograde orbit.  I left it that way for a couple of hours, and there was no collision.  In another flyby, Sandra approached Umbilical at a mere 6000 km and hardly did anything to Umbilical's orbit.  These objects are moving so fast that they don't have time to affect the faux moon's orbits.

On the other hand, a binary flyby leaves one object in orbit and the other flung far into the outer solar system (in one case, 19.5 billion kilometers) about half the time if the flyby is close enough.  A lot depends on the particular conditions of the flyby.  If the objects approach and are rotating such that one follows the other at about the same altitude above Neptune, separation is less likely.  It is more likely if one object is significantly closer than the other at closest approach.

Whatever caused Triton to get into orbit around Neptune must have been just about the same size as Triton.  2003 UB313, the newly discovered Xena, is almost exactly the size of Triton, if current measurements are correct.  I believe they are.  Since Xena has a moon (which I think formed later via a collision with a KBO), we will soon find out.


Title: Re: Were Triton and 2003 UB313 once part of a bina
Post by frankuitaalst on 11/07/05 at 13:45:11

Hallo ,

I downloaded the simulation of triton as you mentionned in the link. It worked , but starting the simulation it seems that all the planets etc. vanish .After a second nothing more is there as the edit box tells me .
Can you explain what went wrong ?

Regards,
Frank

Title: Re: Were Triton and 2003 UB313 once part of a bina
Post by Michael_C._Emmert on 11/07/05 at 14:52:44

Hi, frankuitaalst;

I believe I sent it with the time paused :-[.  Anyway, start the time.  Go to the bottom right corner to "focus object" and focus on Neptune.  Go to "screen scale" and push + until you get to 2.642 AU.  Go to "Time Step--Seco"(nds) and increase it to 64 seconds.

It will take some time for Vicki/Sandra to get to Neptune.  Go to "View" then "Dashboard Elements" and push the "P" button.  Wait 4 minutes.  Then push "P" again.  Vicki/Sandra will be much closer to Neptune.  Zoom in to watch the fireworks.

I obviously need to make a more viewer-friendly simulation.  This one works, but thanks for asking.  I now realize that I do need to work on this.  I had considerable experience when I made the simulation, but NONE sending it in and having it viewed by people who just got GravitySimulator.  Sorry.  Back to the drawing board!

Mike.

Title: Re: Were Triton and 2003 UB313 once part of a bina
Post by frankuitaalst on 11/10/05 at 11:53:49

thanks Mike , It worked ...!
Very nice simulation

Regards ,
Frank

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