Nickel+Supernova

A supernova is a massive explosion caused by the collapse of a huge star (usually ether a blue giant or red super giant). A star starts its life as a big cloud of gas and other particles. It then forms a great big ball of gas called a star (like our Sun). If it is big enough it will blow up as a supernova in a couple million years. When the supernova is created, there are lots of neutrons and electrons whizzing around and so lots of new atoms are created. Nickel is one of these atoms.

References: Wikipedia-Supernova nucleosynthesis