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Message started by frankuitaalst on 08/12/07 at 07:10:54

Title: Kuiper belt objects
Post by frankuitaalst on 08/12/07 at 07:10:54

In Annex a .gsim simulation in which some hypothetical Kuiper belt objects are added to the SolarSystem .
Sim was created out of the SolarSystem.gsim , adding 5 additional objects , each residing at rest at 100 AU from the sun , also far beyond Pluto .
If the sim is run initially at around 8000-16000 timestep one can see the Kuiper objects move as arrows towards our sun .
It is usefull to keep track of the distance of the closest object and reduce the time step since the objects get velocities of about 30-40 km/sec in the neighbourhood of Earth and even up to 1000 km/sec close to the sun !  

Title: Re: Kuiper belt objects
Post by frankuitaalst on 08/12/07 at 07:16:39

Here is a screenshot of this simulation.
I started with T=16000 sec. and reduced the timestep to 1 second when an object comes close to the sun.
Starting with 5 objects the first hit the sun and 2 were ejected .
The 2 remaining ones resume their highly eccentric orbit .

Title: Re: Kuiper belt objects
Post by frankuitaalst on 08/12/07 at 07:23:34

Plotting the distance to the sun of such on orbit versus time can produce a plot as following .
Time to get to the sun for such an object is about 180 years ( starting at 100 AU ) .

Title: Re: Kuiper belt objects
Post by frankuitaalst on 08/12/07 at 07:52:20

Distance and velocity plots may look like these ...
Dependend upon the initial position the plots may vary as the body may be influenced by the outer planets
( cfr animated gif where it is clear that not all bodies arrive at the same time around the sun , due to perturbations of the outer planets ) .

Title: Re: Kuiper belt objects
Post by Tony on 08/12/07 at 12:43:41

I like the graphs.  Why are you giving them 0 initial velocity, instead of orbital velocity?

You and I are both thinking outer solar system.  I've got a sim running trying to simulate the formation of the Oort Cloud.  I'm not having much luck.  I'll post the results when I'm finished.

Title: Re: Kuiper belt objects
Post by frankuitaalst on 08/13/07 at 13:00:01

I used zero velocity just to find out how they would arrive in our inner solar system and if some of them were able to miss our sun . It seems to be so . Also it is commomly known that comets may be born in the outer regios , residing there and for some reason start to head for the inner solar system . Giving tem a velocity of about 2km/s would keep them in orbit .
Concerning the Oort cloud I think this must be very difficult to simulate as not much is known about initial conditions and there must be a huge number of bodies involved , or am I wrong .

Title: Re: Kuiper belt objects
Post by Tony on 08/13/07 at 16:06:19

There are many bodies, trillions in fact.  But I'm not simulating that many  ;)

I started by placing the Sun in a star cluster with 20 other solar-mass stars.  The cluster had a diameter of about 1/2 light year.  Jupiter-Neptune are orbiting the Sun, as well as 80 test particles.  As these particles encounter the planets, they are boosted into eccentric orbits with high aphelions.  From time to time, a close stellar passage raises the perihelions of the eccentric test particles out of the planetary region.  They are now Oort cloud members.

The trouble I'm having is that not that many objects become permanent Oort Cloud members.  And none of them are boosted as far as 50,000 AU, the theorized distance of an average Oort Cloud member.  1000-2000 AU is about the best I get before they get stripped away from the Sun.  My star cluster is rather small for 20 stars.  So I may try this again with different starting conditions.  I'm only trying to identify trends.

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