Iron age

Stars fuse hydrogen into helium through much of their lives. As they age, they run out of hydrogen, and some begin fusing the helium into carbon, and so on up to iron in the most massive stars.

Petersen, C. C. (2015). Astronomy 101. Adams Media.

http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/imgnuk/bcurv.gif

The element iron (Fe) is most stable as the binding energy of its protons and neutrons is highest.