Every star undergoes a long, marvelous journey called stellar evolution. Stars are born, live, and die in cycles spanning millions or even billions of years. The life cycle of a star, like our Sun, ultimately leads to the formation of a white dwarf. But how does this transformation occur?
Stars, including the Sun, spend the majority of their lives in the main sequence phase, where they fuse hydrogen into helium at their cores. This energy production creates an outward pressure balancing the inward force of gravity. Over time, stars run out of hydrogen fuel. For solar-type stars:
- Once the hydrogen is depleted, the core contracts starting to fuse helium.
- This process swells the star into a red giant.
- Eventually, the outer layers are expelled as planetary nebulae, leaving behind the dense core—a white dwarf.
Understanding this progression helps us make sense of objects like the white dwarf in the Helix Nebula. Such dwarfs are the remnants of what were once shining, burning stars, now concluding their evolutionary path.