Your scenario would result in a planet (or a few). Any part of the disk that is denser than the surroundings -- even slightly -- will pull more material into it from all sides. Or even by random chance, some asteroids will clump into a more massive one than average, resulting in a similar instability. Rather than forming a solid ring, the disk would fragment into one or more protoplanets that sweep up or scatter away the rest of the material. Basically this is the planet formation process, though starting from asteroids. By increasing the mass of the disk you just make the process faster.
The Orion Nebula contains many stages of star formation, and it is an emission nebula because it has already formed a number of stars which have ionized the surrounding gas. There are also some parts of it which are currently forming planetary systems (proplyds
If you're interested in what collapsing molecular clouds look like when they are about to form stars inside them, they are opaque, especially in their cores where the protostars are forming. We cannot observe all stages of star formation in visible light.
Propulsion Disk wrote:
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Your second paragraph says that "gravity pulls things into spheres" witch is not true because otherwise galaxies would be spheres.
We're talking about solid objects formed from gravitational collapse. Galaxies are not solid, nor collapsed fully (if they were they would be black holes).Gravitational collapse forms disks when the particles have too much angular momentum to collapse further, and also are able to collide and settle into a preferred plane.