[kakacik]

But why? Star forms when enough hydrogen (or maybe also helium) clusters together with gravity to spark fusion IIRC. The center of Milky way ain't some ultra dense place where stars are just trillions of kms from each other to support somehow earlier star formation.

Or did ie dark matter/energy somehow coalesce on the outer edge later? Milky way is supposed to be very old place, almost as old as universe itself so one would expect more homogeneous distribution, at least as a layperson.

[Ekaros]

You need certain density to start formation progress. Then you get more density as it drags more stuff via gravity from intergalactic void. So new stars form at edges when there is finally enough stuff pulled by gravity of whole galaxy to there for the formation to happen.

It seems that you need quite large concentrations(as in scale of whole universe average) to actually get to star formation. Otherwise stars would be uniform trough the universe.

Then again I am not astronomer.

[addaon]

> Then you get more density as it drags more stuff via gravity from intergalactic void.

The pre-stellar cloud has the same mass, and thus the same gravitational impact, as the stars that form from it.

[dotancohen]

> You need certain density to start formation progress.

Aren't fluids (such as a hydrogen gas cloud) densest at the bottom of a gravity well? It would be expected that the nearer one is to the galactic center, the denser the intergalactic medium would be.