Lifecycles of Stars: What Causes Gravity in the Beginning?

[mrhessy]

I'm a relative newcomer to astronomy and am still trying to understand the lifecycles of stars, i think i understand that the beginning stages of stellar evolution involve hydrogen atoms being pulled towards a central area of gravity, but where does the gravity come from?

 

[Astronuc]

Gravity originates with the mass. Remember, the clouds are very large.

http://en.wikipedia.org/wiki/Nebula - no details, but basic information.

Some information on the size of nebulae - http://faculty.rmwc.edu/tmichalik/PlanetaryNeb.htm