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adamskiiix
2011-Sep-16, 09:00 PM
ok, i just read the thread about the protostar forming in the region 27ly away from earth and one thing got me puzzled a little (yes it took me a while to realize that). When the star is forming it occurs when dust and gas collapses under its own gravity producing pressure and heat that ignites the star.. that is quite clear to me. Also the reason why stars end up as white dwarfs, neutron stars and black holes respectively due to battle lost to gravity over pressure. But why actually the gas and dust that its a building block of a star doesnt collapse directly into neutron star or black hole without actually forming a star, i mean the amount of material is the same or actually more because stars give up some of its mass due to coronal ejections? tell me when i began to eer;]

thanks,
adamskiiix

Hornblower
2011-Sep-16, 10:09 PM
ok, i just read the thread about the protostar forming in the region 27ly away from earth and one thing got me puzzled a little (yes it took me a while to realize that). When the star is forming it occurs when dust and gas collapses under its own gravity producing pressure and heat that ignites the star.. that is quite clear to me. Also the reason why stars end up as white dwarfs, neutron stars and black holes respectively due to battle lost to gravity over pressure. But why actually the gas and dust that its a building block of a star doesnt collapse directly into neutron star or black hole without actually forming a star, i mean the amount of material is the same or actually more because stars give up some of its mass due to coronal ejections? tell me when i began to eer;]

thanks,
adamskiiix
The progress toward the ultimate collapse is slowed down first by the heat of compression, which takes a while to escape, and then by the heat generated by nuclear fusion when the core gets hot enough to induce that fusion. Eventually all of that heat is exhausted, and the star settles down into its final state. For under 1.4 solar masses, that is a white dwarf which is supported by quantum mechanical electron degeneracy pressure even when stone cold. Above that mass gravity crushes the electron structure and the result is a neutron star, supported against further collapse by the corresponding neutron degeneracy. If we have a few more solar masses, gravity crushes everything and we have a black hole.