Which stars are made up of concentric layers of different chemical elements, up to and including iron?

Stars with a mass of more than 5 M become layered as thermonuclear reactions develop. The outer layer consists of hydrogen and helium, below is a pure helium shell, and even deeper are shells of carbon, oxygen, manganese, silicon. In the center, an iron core is formed.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.