Under what circumstances will a binary white dwarf star be able to begin to strip mass off it's companion?

 

White dwarfs are among the densest star in space. they can have approximately the mass of the sun but in size they have roughly the radius of Earth. The mass is very compact in an incredibly small size. This makes them among the densest objects in space, beaten out only by neutron stars and black holes.

Same with other stars, the white dwarf is also going through with some sort of struggles regarding its mass.

When it runs out of fuel, it no longer experiences an outward push from the process of fusion, it rather collapses inward on itself.

White dwarfs reach this incredible density because they are collapsed so tightly that their electrons are smashed together, forming what is called "degenerate matter."

In the case of a white dwarf in a binary system, it may be able to pull material from its companion onto its surface. Increasing the white dwarf's mass. the white dwarf will start taking materials from its companion before it fades away into relative obscurity, eventually radiating away all of their energy and becoming so-called black dwarfs; which is the fate of many white dwarfs.

That also happens if the white dwarf is more massive than its companion and if both are close enough to each other, the gravity of the white dwarf can pull matter away from its companion.

One possibility is that the added mass could cause it to collapse into a much denser neutron star.

At other times, the white dwarf may pull just enough material from its companion to briefly ignite in a nova, a far smaller explosion. Because the white dwarf remains intact, it can repeat the process several times when it reaches that critical point, breathing life back into the dying star over and over again.