Which life cycle stage is unique to a massive star?

The life cycle stage that is unique to a massive star is the supernova. Massive stars undergo a more complex evolutionary path compared to their smaller counterparts. After spending a considerable time on the main sequence, fusing hydrogen into helium, they expand into red giants as they start fusing heavier elements, ultimately leading to their demise.

Once a massive star has exhausted its nuclear fuel, it cannot support its own gravity, leading to a catastrophic collapse of the core. This collapse results in an immense release of energy, producing a supernova, which is a powerful and luminous explosion that marks the end of the star's life cycle. This phenomenon is specifically associated with massive stars; less massive stars typically end their lives in a gentler fashion, often resulting in a planetary nebula rather than a supernova.

Thus, the supernova stage is a defining characteristic of massive stars, setting them apart in their evolutionary process.