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solar system generator (Read 7534 times)
frankuitaalst
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solar system generator
05/10/10 at 11:16:09
 
I would like to share the results of some simulations I've made during the last days about solar system generation .  
In annex is a representative file you can run in GravSim .  
It consists of 100 masses , each having a mass of 0.5 earth mass , each having a diameter of 20000 kms and orbiting our sun at 1AU .  
(Easily done :  Create --> 100 ; 10000 km radius , 1AU , 0 ecc , 0 incl , 0.5 Earth mass ...Run at 128 sec ) .  
One after one the objects start to merge ....
What happens ?  
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frankuitaalst
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Re: solar system generator
Reply #1 - 05/10/10 at 11:21:23
 
Here's an animation of such a run , which shows whats happening :  
The objects interfere , some are growing larger and push other objects in higher eccentricies , lower or higher orbits , and merge again , until only a few planets are left at the end ....
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100Earths.gif
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frankuitaalst
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Re: solar system generator
Reply #2 - 05/10/10 at 11:29:20
 
What happens ?  
How many planets are left at the end ?  
How heavy are they ?  
Will the orbit as large planets near the sun or as small planets far away ?  
Will the heavy planets orbit inside and the smaller outside or vice versa ?  
Here's an animation of the results of about 15 different sims I've run ...
The smallest planets are in green , the biggest in red , the middle sized planets in yellow ...
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SolarSystemBuilderResults.gif
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frankuitaalst
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Re: solar system generator
Reply #3 - 05/10/10 at 12:42:27
 
Here's some statistical information of the 27 sims I've run so far ....( all the sims had the same initial values , with exception of the values generated by the random generator for the mean anomaly , ascending nodes ...aso ) .  
 
1. Number of planets :  
in most cases 3 planets were left ; in only one case I got 4 planets . No system ended up with 1 planet .  
 
2. Masses of the planets :  
The blue line represents the innermost planet , the red one the second planet , the third planets mass is represented in green.  
The outermost planet mostly has the lightest mass .
In some cases the innermost planet is most massive , in other cases the second planet gets the biggest mass .  
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Frequency_Masses.jpg
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frankuitaalst
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Re: solar system generator
Reply #4 - 05/10/10 at 12:51:00
 
The mass distrubution seems to be dependent upon the number of planets left at the end as can be seen in the representation hereunder :  
From the first graph ( 2 planets ) it is clear that the innermost planet has as tendency to be bigger than the outermost .  
The second graph (3 surviving planets ) shows that the most massive planet will mostly be the second planet . The outermost planet being the least massive .  
 
Some other observations :  
- in these systems no planets were generated with retrograde orbits , neither at the end , neither in the evolution of the system itself .  
- no system ended with 1 planet left , no system had more than 4 planets .  
 
It may be interesting to run more simulations in order to get some statistical values ...
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Frequency_masses_2.jpg
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EDG
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Re: solar system generator
Reply #5 - 05/11/10 at 08:56:58
 
Very interesting. I guess you don't have more planets because of the number of bodies that you start with? And also I guess because it's probably not practical to run a simulation where the planetesimals extend several dozen AU from the star, because it'd take forever to run it.
 
Though 10,000 km radius is pretty huge - essentially you have 100 fully formed (and very large) planets there, not small planetesimals that actually clumped together to make the planets. I'd knock the radius and mass down a lot and increase the number of bodies to compensate (but again, that creates processing issues Smiley ).
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frankuitaalst
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Re: solar system generator
Reply #6 - 05/11/10 at 09:06:32
 
Quote from Mal on 05/11/10 at 08:56:58:
Very interesting. I guess you don't have more planets because of the number of bodies that you start with? And also I guess because it's probably not practical to run a simulation where the planetesimals extend several dozen AU from the star, because it'd take forever to run it.

Though 10,000 km radius is pretty huge - essentially you have 100 fully formed (and very large) planets there, not small planetesimals that actually clumped together to make the planets. I'd knock the radius and mass down a lot and increase the number of bodies to compensate (but again, that creates processing issues Smiley ).

You're right in your comments . I took the AU small and the diameter large in order to speed up the process .  
I've run also a sim with AU initial equal to 2 and 5 AU . Takes a lot more time to simulate .  
My guess is that the number of surviving planets increases with growing AU initial .
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atomic7732
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Re: solar system generator
Reply #7 - 05/13/10 at 16:31:07
 
I'm running a similar sim. I halved everything, but I double the amount of objects... I'm waiting to see how it will turn out.
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atomic7732
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Re: solar system generator
Reply #8 - 03/21/11 at 16:03:02
 
I'm not sure the results of the simulation that I was talking about... But now, I am running a simulation, well 3, that are initially 75 .5 earth mass worlds at a timestep of 1024.
 
Odd that my original simulation is the slowest... at 768 years, and my newer are already at 960 and 2000.  
 
System 1 contains 2 planets, as does system 2, and system 3 contains 4 bodies with masses of at least 3 earths, which i randomly chose as the limiting mass to call it a planet.
 
Pictured: System 2 and 3
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systemcreator_3.png
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atomic7732
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Re: solar system generator
Reply #9 - 03/21/11 at 18:32:08
 
These systems finished, with 3 and 2 planets. The first simulation looks like there will be one dominating planet.  
 
frank, I have to disagree. hill spheres become larger the further from a star, and so I think the further you get from the star the less planets you will get. At over 10 AU most likely you will end up with 1 planet over 80% of the time.
 
I have my data here: https://spreadsheets.google.com/ccc?key=0AgTvxKfJlBKWdEdadlFjQXNEenBmN2g5NXhkZzh
fZGc&hl=en&authkey=CJiMu5cC
 
I think the reason the middle planet of the 3 planet systems is the most massive is because there are a few planets that start to from and scatter the others. The largest one dominates and eats over half of the material. The leftovers are there for the smaller planet seeds that get scattered to devour.  Smiley
 
Criteria for a "planet" in a stable system is: any body that doesn't cross another body with mass greater than or equal to it.
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« Last Edit: 03/21/11 at 21:34:03 by atomic7732 »  
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