In massive stars, a complex series of nuclear reactions leads to the production of iron in the core.Hypergiants emit hundreds of thousands of times more energy than the Sun, but have lifetimes of only a few million years.

From the Remains, New Stars Arise.In a supernova, the star's core collapses and then explodes.

McNeil's Nebula, they found something interesting its brightness appears to vary.Along with main sequence and white dwarf stars, other groups include dwarfs, giants, and supergiants.Aside from our sun, the dots of light we see in the sky are all light-years from Earth.