Quote:
Originally Posted by QuantumJo
Why do they spin?
A star is formed when gas and dust compress due to gravitational forces and collapses under its own weight. What I wonder about is why does the new star start to spin. What force is responsible for this? I have done some research on angular momentum but I am still not clear on what starts the rotation.
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http://www.pbs.org/deepspace/experts/week1b.html
The guy in the link above says tidal forces between the various objects in the cloud, which is probably correct.
If I had to guess off the top of my head, it might have something to do with the curvature of space around massive objects, but I'm just guessing here, I didn't look it up or do any calculations. If a particle has an initial velocity and enters a gravity well of another object, unless it was initially heading directly at the center of mass, the trajectory would curve toward the center of mass so if it was captured I think it would spiral into the gravity well. Think of a marble being flung into the top of a horn shaped tube but not right down into the hole, a bit off to the side, it spirals around as it goes down to the bottom. I'm guessing that as a bunch of them come together, the angular momentum of the resulting collapsed cloud would be non-zero and the resulting object would be spinning no? The rate of spin would then maybe be proportional to the non-uniformity of the original cloud? I'm not an astrophysicist though, so I might be full of it
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