How does a star become a black dwarf?

2 Answers
Jan 2, 2016

When a star the mass of the Sun dies, it becomes a white dwarf.

Explanation:

The white dwarf is a small, dense star and over the course of trillions of years, it shines. But when it runs out of energy, it slowly dims and becomes a black dwarf. Black Dwarfs are not present in this time, as they take trillions of years to form and the Universe is only 13.8 billion years old.

Jan 2, 2016

After the White-Dwarf Stage.

Explanation:

A main sequence star when it has consumed all of its hydrogen to helium will rearrange and transform itself into a red-giant Star as its core will shrink and outer layers will expand. The Size of the Sun in its main sequence stage is about 0.1 AU but in its Red-giant state the Sun will be as big as 2 AU.

In the Red-Giant stage, the Sun will burn helium to Carbon and also oxygen and when it is out of these elements it will shed its outer layers into Space forming a planetary nebula with a White-Dwarf at the center, a small extremely dense Star about the size of the Earth.

It is hypothesized that when a White-Dwarf cools in about 100 Billion years or so it will no longer be able to radiate any heat and turn Black-the concept of Black-Dwarfs.