When all the elements were used up it tried to fuse one last element- iron.
Iron is stubborn and does not permit fusion. Well, it does, but it doesn't produce much energy at all.
The problem with this is that as the star was fusing different elements it became larger and larger and much more massive. More mass = more gravity. More gravity = more energy needed to maintain size. Not enough energy to maintain size = implosion. The implosion is called a supernova. Think about it- there is no outward pressure preventing the inward pressure from winning.
This is where it gets really interesting.
After the supernova most stars turn into an unimaginably dense star called a neutron star. These neutron stars are many times smaller than the original star that blew up. The process of collapsing takes roughly 10-20 seconds. So much energy is produced in the implosion that the dying star outshines its ENTIRE GALAXY for a period of time. Eventually the supernova (over many many years) dissipates and the neutron star fades into a cold darkness.
Now after the supernova occurs and the star implodes on itself there is another option. If the resulting neutron star is large enough it will undergo a terrifying and dramatic transformation. Sometimes the pressure of the implosion on the neutron star is too much for the unimaginably dense star to handle. In fact, nothing can handle the gravity created by some collapsing stars.
You know where this is going. No force can stop the implosion and the light from the star disappears into its collapsing core. All matter disappears into the its collapsing core. EVERYTHING disappears into its collapsing core. A black hole is born.
So back to the star that tried to fuse iron 10 billion years ago. It fused the iron, it blew up in a massive light show, and, well, the rest of the story is unknown. What is amazing about this is that we are JUST seeing the light from this supernova. Why? Because we are 10 billion light years away from the star that blew up.
Now it gets sad, because even though we are seeing the light right now, we are seeing something that happened 10 billion years ago. It is all but guaranteed that the supernova is gone, the star is either a cold dead neutron star or a black hole sitting in space waiting for anything.
Then again, if we were at the location of the star looking back at Earth, our star would not even be here, let alone us.
There is a happy ending here. You, yes you reading this, would not exist unless the stars in the universe die. They release the elements necessary for life and your body contains massive amounts of stardust. We were all given the building blocks of life because a star died.
Anyway, if you want to read more about this 10 billion year old supernova check out this link and thanks for reading: http://www.space.com/20509-most-distant-supernova-found.html?cmpid=514630"