answersLogoWhite

0

A dying star is a star that no longer has enough hydrogen nuclei (free protons) to sustain the thermonuclear fusion reactions that permit its core to combine four hydrogen nuclei to form one helium nucleus. Astrophysicists have developed excellent understanding of the death of stars, although new details do continue to emerge. Understanding the death of a star is easier if you keep in mind that most of the star's mass is in its extremely dense core; its outer regions make up most of the star's volume but contain relatively little matter compared to the core. The "life" of a star is in its core. A dying star goes through several predictable stages, depending on its mass. Except for the very smallest stars, the death of a star begins with a dramatic collapse of its core and an expansion of its outer regions to form either a giant or supergiant. When this happens to our Sun, its outer photosphere (the only part that gives off light) is likely to extend to somewhere near the Earth's orbital path. The core of a giant or supergiant dying star is hot enough that helium nuclei can be fused to form the nuclei of heavier elements. At some point, the dying star can no longer continue any sort of fusion process and the core erupts explosively. For a medium-small star like our Sun, this eruption is relatively gentle; all of the outer shell will be blown away, but the core will remain relatively intact. Scientists call an intact core like this a white dwarf; a white dwarf eventually cools to become a black dwarf. In dying stars somewhat larger than our Sun, the core collapses even further to form a very small but very massive remnant called a neutron star; the formation of a neutron star explosively releases a huge amount of energy called a supernova. The very largest supergiants leave remnant cores called black holes which are so dense that not even light can escape from their gravitational field.

User Avatar

Wiki User

16y ago

What else can I help you with?