* Nuclear Fusion: Stars generate energy through nuclear fusion, combining lighter elements into heavier ones. In the core of a low-mass star, hydrogen atoms fuse to form helium. This process releases immense energy, providing the outward pressure that balances the inward pull of gravity, keeping the star stable.
* Helium Accumulation: As hydrogen is consumed, helium builds up in the star's core. Helium is more stable than hydrogen and requires a much higher temperature and pressure to fuse.
* Insufficient Mass: Low-mass stars lack the necessary mass to generate the immense gravity and pressure needed to initiate helium fusion. The core temperature never reaches the required threshold.
* Red Giant Phase: As hydrogen fuel dwindles, the core contracts and heats up, causing the outer layers to expand and cool. This transforms the star into a red giant.
* Helium Burning: Eventually, the core becomes hot and dense enough for a brief period of helium fusion to occur in a shell surrounding the core. This process produces carbon and oxygen but is relatively short-lived.
* White Dwarf: After helium burning ends, the core of a low-mass star cools and shrinks into a dense, compact object called a white dwarf. This white dwarf is primarily composed of carbon and oxygen.
In essence, low-mass stars lack the sufficient mass to sustain the high temperatures and pressures needed to fuse elements heavier than helium. This limits their evolution to a point where they are primarily composed of helium.
