Or you could just have a big object tossed in close to the star. It goes into orbit and it will get torn apart by the gravity of the star once it gets close enough.

252

If we don't detect metal rich dust around the other white dwarves, we might have to revise our thinking [about the dust's origin], ... The comet impact model looked pretty good 10 years ago, but it doesn't look so good anymore. There's still a lot of mystery.

191

Something's got to be replenishing these metals, ... The suggestion is maybe this white dwarf had planets around it, and the system was substantial enough that after billions of years of grinding, there's still enough material to feed the dust disc around the white dwarf.

129

It's possible they were formed by some object getting tossed in too close to Saturn and it got torn apart by gravity.

105