Here's why:
* Fusion Process: Stars generate energy through nuclear fusion, fusing lighter elements into heavier ones. Low-mass stars like our Sun can only fuse hydrogen into helium. High-mass stars, however, can fuse heavier elements like carbon, oxygen, silicon, and eventually iron.
* Iron's Role: Iron is the most stable element in the universe. Fusing iron requires energy input instead of releasing energy. This means that when a high-mass star starts fusing iron, it's a sign that the star's core is running out of fuel. This event triggers the star's collapse and a spectacular supernova explosion.
* Evidence of Past Supernovae: The presence of significant amounts of iron in a star or stellar remnant like a white dwarf is a strong indicator that the star was once a high-mass star.
In summary: While low-mass stars can fuse hydrogen into helium, high-mass stars can fuse heavier elements, culminating in the fusion of iron, which ultimately leads to their dramatic demise in a supernova.
