Investigate the types of nucleosynthesis reactions involved in Main Sequence and Post-Main Sequence stars

From the Universe to the Atom > Origins of the Elements >

Proton-Proton chain

Step 3, which produces , depends on the temperature of the star

• For temperature between 10-14 MK , helium-4 is produced by fusing two helium-3 nuclei.
• For temperature between 14 – 23 MK and exceeding 23 MK, ³He fuse with pre-existing ⁴He to form beryllium-7, which undergoes further reactions to produce two helium-4 nuclei.

– CNO (carbon–nitrogen–oxygen) cycle

CNO cycle: common in larger stars – uses C as a catalyst and requires hotter temperatures

Extract from Physics Stage 6 Syllabus © 2017 NSW Education Standards Authority (NESA)