Do massive stars burn heavy elements like Carbon early in their life course?
Massive stars produce concentric shells of elements as their cores produce heavier elements as “ash” of the previous burning. So a massive star has an outer shell of unfused hydrogen, then a shell of helium, then a shell of carbon, then one of neon, then one of oxygen, then one of silicon, etc. until the core is composed of iron (the final element that can be created by fusion). There is some fusion going on in each shell, but the majority of the energy is produced at the core. As the energy of fusion in the core fades when that fuel starts to run low, the star starts to collapse a little and this drives the temperature in the core high enough to start fusing the “ash” of that previous burning. So when the helium starts to run low, the star collapses a bit from the reduced heat, and this drives the temperature in the core high enough to start carbon fusion. And it keeps going like that until there is only iron in the core – at that time there is nothing to fuse even with higher tempera
