phenomena star death

Main-sequence stars generate energy by nuclear fusion of hydrogen in their cores. When supplies are exhausted, they find a new source of power—burning the helium they have spent their lives generating, and perhaps other, heavier elements. These changes in the star's energy supply make it unstable, causing it to swell to giant size. The star's ultimate demise is determined, like most aspects of its evolution, by its mass.


The most massive stars may eventually detonate in supernovae, leaving behind a neutron star or a black hole. Sun-like stars become red giants, before collapsing into white dwarfs, while the least massive stars simply dwindle away.

\ low-mass star \ star collapses and evolves into a black dwarf (0.1 solar masses)

\ high-mass star (8 solar masses)

dense black hole

\ collapsing star at heart of planetary nebula

\ high-mass star (8 solar masses)

\ collapsing star at heart of planetary nebula neutron star dense black hole giant stars

When a star has exhausted the hydrogen at its core, the hydrogen-burning process moves out into a spherical shell. The star becomes much brighter, but radiation from within makes its core develops onioniike layers

gravitational force acts inward the heaviest element produced is iron new fusion reactions produce sodium, magnesium, silicon, sulfur, and other elements the heaviest element produced is iron gravitational force acts inward outward pressure exerted by radiation in core outer layers balloon and cool. Stars like the Sun become red giants, but more massive and luminous stars can become supergiants of any color. Inside the giant, the core itself collapses, until it becomes hot and dense enough to burn helium. The star then stabilizes, shrinking back to a more normal size for however long the helium lasts.

giants and supergiants

Many of the sky's brightest stars are giants—their high luminosity makes them brilliant at far greater distances than normal stars. This list includes red giants as well as even more massive supergiants.

name magnitude type constellation red supergiant star

Gases in any "layer" are trapped between two equal and opposing forces—the inward pull of gravity and the outward pressure of radiation. As the intensity of radiation varies, the star can expand and contract.


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