Stellar Middle Age and Maturity:

Main Sequence Evolution

A star’s luminosity increases gradually over time as its core composition changes

Life Expectancy

The more massive a star, the shorter its lifespan, as it burns through its fuel faster.

Red Giant Phase

After exhausting core fuel, the star expands into a red giant or supergiant, initiating shell fusion.

Triple-Alpha Process

If the core gets hot enough, helium nuclei fuse into carbon. The star temporarily contracts, but then expands again as fusion in the outer layers continues.

Star’s Fate

Higher mass stars can continue fusing heavier elements, but eventually, the core collapses and outer layers are expelled.