For stars less than 8 times the mass of our Sun:
* White Dwarfs: These are incredibly dense objects, about the size of the Earth, made up mostly of carbon and oxygen. They slowly cool down over billions of years.
For stars between 8 and 20 times the mass of our Sun:
* Neutron Stars: These are even denser than white dwarfs, with a radius of only a few kilometers. They are made up primarily of neutrons and have incredibly strong magnetic fields.
For stars more than 20 times the mass of our Sun:
* Black Holes: These are objects with such immense gravity that not even light can escape. They are formed when a massive star collapses under its own gravity, creating a singularity of infinite density.
Other possibilities:
* Supernova Remnants: The explosion of a massive star (supernova) can leave behind a cloud of gas and dust called a supernova remnant. These remnants can be quite large and complex, and can eventually lead to the formation of new stars.
* Pulsar: A rapidly rotating neutron star that emits beams of electromagnetic radiation.
So, the answer to your question is not a single thing, but rather a range of possibilities depending on the star's initial mass and the conditions during its collapse.
