A low-mass giant on the horizontal branch fuses hydrogen into helium in its core.The core temperature is insufficient to fuse helium into carbon.So what nuclear reaction does happen next?

Question

Quizplus · Accepted Answer

When the core of a low-mass giant on the horizontal branch is unable to fuse helium into carbon, the nuclear reaction that happens next is shell helium fusion. In this process, the helium fusion occurs in a shell surrounding the core, rather than in the core itself. As helium accumulates in the shell, it becomes hot and dense enough for fusion to occur. This results in the production of carbon and oxygen in the shell, which can later be dredged up to the surface by convection and enrich the star's outer layers.

A Low-Mass Giant on the Horizontal Branch Fuses Hydrogen into Helium