Final answer:
The temperature necessary for the helium flash to occur is around 100 million K. During this process, three helium nuclei collide simultaneously to form a stable nuclear structure and produce a carbon nucleus.
Step-by-step explanation:
The temperature necessary for the helium flash to occur is around 100 million K. During this process, three helium nuclei collide simultaneously to form a stable nuclear structure and produce a carbon nucleus. This high temperature allows for the fusion of helium nuclei despite the repulsion between the positive protons in each nucleus.