A star is a massive, incredibly bright sphere of plasma held together by it's own gravity. Stars are created from the gravitational collapse of a nebula. The closest star to Earth is our star, the Sun. The closest extrosolar star is named Proxima Centauri, and is 16 light years away from our solar system. For a portion of a star's life, it burns brightly due to thermonuclear fusion of hydrogen into helium. Once the star runs out of hydrogen, the star starts burning helium, which turns the star into a Red Giant. Once the star runs out of fuel, there are three different ways a star could die: The star could become a dense and radioactive White Dwarf, it could explode off in all directions, or, if the star is large enough, it will grow larger and larger, but, instead of exploding, will crush itself into a tiny ball and disappear, forming a Black Hole. A black hole's gravity is so strong, not even light can escape it's grasp. This is why we cannot see black holes. However, how a star dies depends on a few things: like how much mass the star has. If the star is too small (like our sun) the star is not massive enough to become a black hole.
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