Why does the PPNe (protoplanetary nebula) model have the outflow poles?
This is pretty much unknown and is one of the hottest topics of astronomy research. Why a disk? Because it’s a stable structure under gravity and also blocks the stellar winds that may disrupt any other structure formation. The winds are probably the force that powers the outflows. Why the infall? Gravity. This is the weak but ultimate long distance force that governs the properties of all structures in the Universe. An interesting note is that while the SS has this predominate spin, the 10 trillion stars and their SS’s (including ours) in the galaxy have each their own random spins and orientations relative to each other, make up a galaxy that is spinning in a very coherent and unified manner in a plane. The plane of our galaxy is composed of SS’s like ours and is flatter than a pancake. It is the same situation in most disk galaxies (they make up 1/3 of the galaxies – the elliptical ones are more like swarms of stars and make up the other 2/3). There are 100 billion such flat galaxie
