Star cluster breakup

[Moontanman]

It is accepted that stars form in dense clusters which break up as the individual stars move away.

 

Why do clusters of stars not gravitationally collapse further into one huge star? What causes these star clusters to break up?

[Raider5678]

I assumed speed of them orbiting?

[Janus]

From my understanding, the only star clusters prone to breaking up are open clusters, which are much more weakly bound together by gravity. They can be disrupted by perturbing effects from other structures or close encounters between member stars which can toss a star loose.

[Airbrush]

I assumed speed of them orbiting?

 

Yes, their relative motion prevents them from falling together into one giant star. Motion is also what prevents all the stars in a galaxy from falling into one giant star.

Edited June 18, 2017 by Airbrush

[stefan r]

The stars form in clouds of gas. We observe open clusters now. The stars we see in the open cluster are moving away from a location that would make them dense. The stars are close to the same age as the time it would take to get from that location to their current location.

 

Protostars grow in size as gas and dust fall in. When anythings falls into a gravity well it releases energy. A lot of mass falling will become extremely hot. Radiation from a hot object will blow gas away. That slows down the rate that gas falls into a particular protostar. The gas cloud continues to collapse but it forms multiple stars instead of collapsing into one. When fusion starts stars will blow gas away in a stellar wind.

 

Three or more similar mass objects usually form unstable orbits. So individual stars get catapulted away. Stars are much denser than interstellar clouds so an ejected star does not experience much drag force.

Edited June 27, 2017 by stefan r