We have seen that a small , up to 1.5 times the size of the , turns into a when it dies. Larger red giants, however, die in a more spectacular way.
Image of supernova remnant by NASA/ESA/JHU/R.Sankrit & W.Blair
Once the nuclear fuel is exhausted in a , the core starts to cool and the internal pressure falls, leading to contraction. In large red giants this is a sudden and catastrophic event so that the star collapses. As the outer layers of the star fall they gain heat. This triggers nuclear fusion in these outer layers and they explode in a spectacular explosion called a supernova, becoming for a few days brighter than a whole .
With so much it is possible to fuse nuclei into even heavier ones such as nuclei. As the star explodes it throws out the nuclei which it has made. On their way out they pick up and become .
The , , , , , and other heavy atoms made by the star are scattered back to in the disc of the . In this way the made in one generation of are passed on to be used by the next.
So all the atoms in your body (except hydrogen) were made in a supernova five billion years or more ago. In this story we will trace their history from the supernova to today. But first we will describe the fate of some different stars after their supernova stage.
What happens to them depends upon the size of the original star.
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