How does a star die?

Death of a star

   Stars burn hydrogen, and when that hydrogen runs out, they die. When they die and how they die, however, differ depending on the size and type of the star. Hot, bright stars die sooner than large, cooler stars. Massive stars violently explode, while smaller stars slowly swell, then shrink to a dim spark. When stars die, they either become black holes (rare), white or black dwarfs (our sun will become a white dwarf), or something called a neutron star.



Death of small stars

  Stars with the solar mass of about half our sun will either become something called a white dwarf or a red giant. These small stars do not collapse in upon themselves. Instead, they do one of two things: They either simply stop burning (in the case of very small stars) or the center of the star, which is usually still surrounded by some remnants of hydrogen, will fuse, causing the star to expand very slowly. These latter stars are actually called red giants, and they are more common than white dwarfs.
   Scientists speculate that white dwarfs will eventually cool down enough to become something called a black dwarf, but they have not been able to prove this, since black dwarfs would necessarily actually have to be older than the universe currently is. This means that the universe hasn't been around long enough to let any white dwarfs form into black dwarfs!

Death of big stars

  Very large stars (categories by solar masses above 8) will look much like a red giant, but the core of the star will be busy triggering nuclear fusion reactions, with the eventual result of the formation of iron, which collides with other gasses and causes a huge explosion. This explosion is called a Supernova. Supernovas are incredibly bright and very rare.The last one happening in our galaxy took place in the seventeenth century and was so bright it could be seen during daylight hours.
   The gravity at the core of the star, and then supernova, will continue to pull the remains of the explosion towards itself, eventually forming something called a neutron star, which is incredibly dense (weighing trillions of tons).
   Stars that have an even larger solar mass (30 or above) will continue to collapse after the supernova to the point where they form black holes, an exceedingly rare event. The gravitational pull of a black hole is so strong that no energy can escape it, not even light.



                                    Here is an awesome short film showing the death of a star: