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