What is the sequence of events leading up to the white dwarf stage?

Answer 1

Here is an answer based on a typical star like our Sun. It's slightly simplified.

If you need more detail Wikipedia's "Stellar Evolution" is useful, but a bit complicated.

An easier introduction is given by NASA in the "Sources and related links" below. Just click on that link if you wish.

All stars will eventually exhaust their supply of hydrogen, the main fuel of every star in the universe (and most abundant element in the universe). The main process of fusion that powers all stars converts hydrogen into the heavier element helium (see "fusion" for more details).

For a star with the mass of our Sun, each second millions of tons of hydrogen (600 million) are converted to helium, slowly depleting the remaining hydrogen (our Sun started with about 11-13 billion years of hydrogen "fuel").

When the hydrogen supply runs low, the Sun will expand, reaching the "red giant" stage of its life.

Eventually the core will become hot enough to fuse helium. The process of fusion will then continue with the helium, along with some remaining hydrogen.

The helium will be converted to carbon, continuing to power the star.

A quite complicated situation arises with hydrogen and helium "burning" at different levels in the star.

Fusion stops after producing oxygen nuclei, because the Sun's temperatures will not be high enough to produce heavier elements.

As the last fuel is exhausted, the star's outer layers will be expelled by the imbalance in pressure from fusion versus the gravity holding the star together. As these outer layers are expelled, the core of carbon and oxygen nuclei will be the remnant, a white dwarf star.

In the beginning there will be a super hot white dwarf emitting light until it cools down and no longer emits light and becomes a black dwarf.

High mass stars, after going supernova, become neutron stars or become black holes, if they're massive enough.