How are white dwarf stars made?

Question

I was told white dwarf stars are burned out normal stars that used up all their hydrogen and then became red giants before a great colapse into very dense matter.

Answer 1

What you were told is true. Or sun is destined to become a white dwarf after it goes through the red giant stage in about another 5 billion years. It will then be about the size of the planet earth. At that time the earth may have been melted into the sun during its red giant stage and, if we are still around then, hopefully we will have learned to live on other planets like Mars.

Answer 2

After the main sequence, most of the nuclear fuel (hydrogen) in the center has been used up. At this stage Helium in the center of star starts burning up and Hydrogen in the outer layer continues to burn up. In this phase the star size grows large and cooler. This star is called Red Giant. While Helium burns up carbon gets left over. Eventually, in the more massive stars, the carbon may burn to even heavier elements, but eventually the energy generation will fizzle out (no fusion stage, as you were mentioning) and the star will collapse to a white dwarf. Astronomers think that white dwarfs ultimately cool to become black dwarfs. These are very dense. No energy is radiated from these stars.

Answer 3

Yes. Red giants continue to expand to form a planetary nebula. The white dwarf is at the center of that. I heard that what is left is mostly carbon, and after many billions (even trillions?) of years, when it finally cools down, it becomes a GIANT diamond! The universe is not old enough to see this happen yet. Can anyone confirm this story? I heard it on a podcast long time ago (astronomycast. a great podcast!)

Answer 4

Ms. K is right, but it's only a crunchy diamond crust, not all the way down. In the high pressures of the interior, you get an ultra-dense electron-nucleus plasma where the electrons are not bound to the nuclei.

Answer 5

Basically, yeah. Read more below:
http://en.wikipedia.org/wiki/White_Dwarf

Answer 6

And you were told correctly.