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Message started by phoenixshade on 01/30/11 at 15:53:28

Title: Collapsing Dust Cloud
Post by phoenixshade on 01/30/11 at 15:53:28

This is a project that I've been running overnight more or less regularly. I tried many varieties beginning with a rotating disk without a large central mass, but none of those have proven satisfactory. So I turned the clock back, so to speak, starting with a much larger, semi-static cloud.

Initially, there are 500 bodies with mass = 1027 kg (about 0.5 MJ), spread over a space with a radius of about 1 LY and very small, randomly-oriented initial velocities. The goal is to see whether a solar-like system will emerge.

So far, the simulation has run for about 23 My. No solar system yet, but the cloud has condensed considerably, and there have been frequent associations of particles that form and disperse.

In the sequence below, each frame represents about 80,000 years.
The First 23 Million Years [animated GIF, 1.24 MB] (

EDIT: Moved attached image to a media hosting service.

Title: Re: Collapsing Dust Cloud
Post by phoenixshade on 01/30/11 at 16:03:59

This is a rotation of the cloud at 8.8 My, giving an idea of the 3-dimensional structure of the cloud.
Rotation through 90, T = 8.8My [animated GIF, 680 KB] (

I'll be putting together rotations at 16.7 My and 22.9 My soon and posting those here as well.

Forgot to mention: In both this and the previous visualization, the screen width is about 55,000 AU.

I will continue to update this thread as the simulation progresses.

EDIT: same reason.

Title: Re: Collapsing Dust Cloud
Post by FedericoP on 07/08/11 at 04:16:21

if I correctly understood you did a simulation of an autogravitating collisionless particles without a central potential well and want to see if it collapses. now,  :) if the initial distribution of particles was three-dimensional (not realistic because of the small number of objects), you reproduced a globular cluster or open cluster. As you can see from your simulation, you can see 3 properties of a very interesting set of self-gravitating objects:

- Equipartition (but ok, only for a mass spectrum  ::) );
- Relaxation;
- Evaporation.

It can, of course, be the same for a 2D cloud with the additional azimuthal diffusion phenomenon which makes three-dimensional the cloud.
if you want, try to allow the collisions.
is a really important addition because it allows you to observe whether or not a central body is formed (black hole for a globular cluster) and allows you to enter a mass distribution of the particles and then allows you to observe the equipartition phenomenon.
But pay attention because you have too less particles and it's possibile that the systems disrupte before you see the equipartition  ;) .

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