Stellar Evolution

6. all that is left after a white dwarf star burns off all of its heat, but retains its mass; a white dwarf that has cooled so much that it no longer emits light or heat
7. a tremendous explosion that occurs when the core of a star is mostly iron
8. fusion, reaction that occurs when the nuclei of two atoms combine to create a new atom. In the core of a star, two hydrogen atoms fuse to become a helium atom, generating energy.
9. a rapidly spinning neutron star
10. a region of gas and dust formed from the cast-off outer layers of a dying star (Despite their name, planetary nebulae have nothing to do with planets.)
11. stage in a star's development when the inner helium core contracts while the outer layers of hydrogen expand, producing a very large red star

1. interstellar clouds of gas and dust
2. a star that is fusing hydrogen atoms to helium; a star in the main portion of its “life”
3. collapsed core of a formerly massive star that was crushed to an extreme density by supernova explosions. The very central region of the star – the core – collapses, crushing together every proton and electron into a neutron.
4. a very young star that is still gathering mass from its parent nebula. It looks like a star but its core is not yet hot enough for fusion to take place
5. a small to mid-sized star that has collapsed
6. a region of space from which gravity prevents anything, including light, from escaping