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Red Giant Stars

Information about Red Giant Stars

  1. The surfaces of all stars are made of pretty much the same things in the same amounts: by mass, 70% hydrogen, 28% helium, and 2% of everything else (note that hydrogen is the least massive).

  2. The insides of stars are different, depending on the type of star, and what stage of life the star is in.

  3. Red stars are cool stars.

  4. Red giant stars are no longer fusing hydrogen in their cores: most of the hydrogen has been converted to helium. So, red giant stars are no longer considered “main sequence” stars.

  5. As blue and yellow stars begin to die, they become larger and cooler. The supply of hydrogen in their cores has been exhausted. The core then collapses, heats up, then begins fusing helium into carbon. Meanwhile, a layer of hydrogen has remained around the core. This hydrogen continues fusing, and the energy produced expands the outer layers of the star. So, red giant stars are very large stars. Because they’ve expanded, the surfaces of red giant stars are cool.

  6. At the end of the red giant phase, the star gently puffs off about 10% of its outer layers. This forms a planetary nebula. The rest of the star collapses until it is about the size of Earth, forming a white dwarf star. White dwarfs no longer generating any energy so they will eventually cool off and become black.

  7. White dwarfs contain as much matter as the sun but are Earth sized. (Consider: the sun has 333,400 times more matter than Earth!) One teaspoon of white dwarf star stuff brought to Earth would weigh as much as a truck or a couple dozen elephants.

  8. The sun will begin this process in 4 5 billion years. When the sun becomes a red giant the Earth's atmosphere and oceans will be evaporated into space. In fact, there is a chance that the whole Earth might evaporate.

  9. Although these stars are referred to as red giants, their color can be red, orange, or yellow.