What is stellar nucleosynthesis?

Answer 1

Supernova nucleosynthesis is the process where new elements heavier than iron are created through nuclear fusion when a star goes supernova. During the "normal" life of a star, it fuses hydrogen into helium, and also fuses lighter nuclei together to make heavier nuclei, at least up through iron. But after the star completes the fusion of much of its bulk into iron, it no longer continues to function as a fusion engine. The fusion processes up through those that produce iron are all exothermic, and this released energy sustains further fusion throughout the life of the star. Toward the end of its life, the star can no longer operate the "regular" way it was in normal stellar nucleosynthesis. Recall that fusion is releasing huge quantities of energy and trying to "blow up" the star, but massive gravity keeps everything together. These two forces, fusion and gravity, operate at equilibrium. After exhausting most of it fuel creating iron, gravity wins and the star collapses. This collapse adds to the star's energy, and the collapse will add tremendous quantities of heat to the stellar plasma. This heat will provide energy for the endothermic fusion reactions that create the trans-iron elements and the star will go supernova, if it is of sufficient mass. With all the extra heat provided by the collapse of a sufficiently massive star, the fusion engine will be jump started. The heat-consuming fusion reactions that create the trans-iron elements will have the energy they need to drive them, and the supernova will create lots of material with nuclei heavier than iron. Additionally, this material will be blown across the universe to fertilize other newly forming solar systems. Links are provided below for more information.

Answer 2

Stellar nucleosynthesis is the process by which stars operate. Stars are massive nuclear fusion engines, and they consume hydrogen, the most abundant element in the universe, and fuse it into helium. They do this throughout most of their lives, and then fuse helium and heavier nuclei to make heavier elements up through iron later in their lives. Stellar nucleosynthesis is the basic "life story" of stars. But what about those elements heavier than iron?

All the trans-iron elements are formed in a supernova event because those heavier-than-iron elements do not liberate energy when being fused. It takes energy to make them happen, unlike the fusion processes that create elements up through iron. The endothermic fusion reactions that create the heavier elements are only possible when the star collapses after exhausting its fuel, and the collapse compresses and heats the material and provides enough energy for the fusion of the heavy elements. A big explosion follows, as you know. And only stars moderately large (a bit bigger than our sun) have sufficient mass to go supernova and create these heavy elements. You'll find links below for more information.
Star fusion is where a star heats up to cause the atoms the smash into each other creating a new mineral which with have a smaller mass that the first. the excess mass is just PURE ENERGY.