Expert: Tom Whiting - 1/28/2009

Question
Good day sir,

I was watching a tv show the other day about our sun and there I caught one particular sentence about how our solar system formed. The way it was described was that there was a huge cloud of different materials - leftovers of a supernova - and all that due to each others gravitational pull just got into one place and formed a star. What was left and did not become part of the sun formed planets, moons, asteroids, etc.

So, I was thinking. What would be the outcome of a computer program that would simulate such a process in a very conventional way. My idea is to have many many particles of different (but not big) sizes and masses, put them inside an area of specific size so that the concentration would be similar in most parts and apply gravity laws. When two of such objects collide they would form a single object that would have a mass and size as big as the sum of the primary objects.

So, would only these two conditions (the gravity and addition of objects) suffice to end up with a huge object in the center and some more objects orbiting it?
Of course, I could just do it and see what happens - this would answer my question. However, I first wanted to consult an expert in this field.

NOTE: I am an amateur astronomer and my main hobby is astronomy along with astrophysics and spaceflight. So, you can use scientific terms and expressions freely - I will understand.

Thanks!

Martin

Answer
Hi Martin,
Yes, this has already been done with very high speed, massive
computers many times over...especially by those groups of people
around the world that are discovering, by indirect means, other
Jupiter-sized planets around other stars, called exo-planets.

It now appears that regular star formation generates planets of
some type around most stars, as seen by the proto-disks around
most of the stars currently forming up in the Great Nebula in
Orion, M-42.
A massive high speed computer is required because this is a very
dynamic process, it's not just two bodies 'colliding' or a supernovae
shock wave hitting a stationary interstellar cloud. It's not that
simple.
And realize that the sun (or star) ends up with, in our Solar System's case, 99.86% of the mass, the planets just being specks of remaining dust circling a....heavy steel cannon ball, by comparison.
And Jupiter ended up with 0.1% so that only leaves 0.04% mass for all
the other...stuff...truly specks of dust as compared to the sun.

It's not so much a collision of bodies, but rather a shock wave of
some form (nearby supernova, spiral density waves in the Milky Way,
etc) plow into a dynamic interstellar cloud of material, causing
it to contract and condense into a star with planetary bodies circling the star. Initially, the collisions are slow enough to
cause bodies to merge (into planets), but later, the collisions are destructive, as with our asteroid belt which was a late planet that just didn't coalesce due to higher speed destructive collisions of proto-planetary bodies. Evidently, (Jupiter's nearby influence
speeded up the proto-bodies in the asteroid belt, so they became
destructive collisions among the asteroid belt region, being a
resonant distance 2.6 AU to Jupiter's 5.2 AU from the sun.)

So since it appears to be the norm...planet formation, the trick
will be to set the gravity and other parameters on your computer correctly, so you get the same result on your computer, as we know it actually happens (and IS happening right now) in nature, so it won't be a case where you can use your computer data to state that...it can't happen; (or convince the rest of the astronomers)....because it DID happen, and is continuing to happen on an on-going basis.
Even those high speed massive computers take weeks and weeks to
run all the calculations required, so you'd better have some very
fancy computer there to do it, or it will take years to complete.
Hope this helps,
Clear Skies
Tom Whiting
Erie, PA

FOLLOW UP:
Perhaps the TV show that you saw, over-simplified all the events
of Solar System formation due to Network time constraints. I wouldn't
put too much faith in complete and literally accurate information...
on a one or two hour TV show, when the actual process of
stellar (and planetary) formation takes millions and millions of years to come to completion. They were only giving the audience the barest of events for time considerations.
Something to think about.
Tom Whiting