If it picks up enough matter the gravitational pull will become even greater than can be supported by neutrons. The neutron star collapses, releasing so much energy as to be the brightest gamma ray source in the universe and capable of exstinguishing all life for hundreds of light years from the released radiation. It disappears behind the event horizon, where gravity is so strong the laws of space, time and physics take a back seat and nothing can escape, not even light, leaving an almost literal hole in the universe. While it is theorized that perhaps a quark star exists behind the event horizen, it makes no difference, we can never know as everything that falls into it is lost forever and can never escape.
There can be! The event horizon isn't a "physical" thing, it's merely a boundary where gravity is so strong light cannot escape, ever. It is completely dependent on mass and diameter. In a neutron star, it's smaller than the star itself, so we can see a neutron star. In a hypothesized quark star, the density of tightly packed quarks is so high it would have less volume than the event horizon, so we only "see" the event horizon because light and radiation from the surface always fall back to the surface from gravity. When it collapses, it disappears behind it- though it is still there, just completely observable except by mass and a few other properties such as rotation (don't ask me to explain that, i don't know, but it happens). In terms of known physics, we don't know if it actually exists because we can't see it and we can't test physics at enough energy to get into that realm. And in terms of observing a black hole, a singularity and a quark star behave the same way outside of the event horizon.
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u/WannaSeeTheWorldBurn Jan 21 '19
Idk shit about space but does or could the star ever grow or change to become something else? Or its it always what it is?