Scientists Said These Stars Were Too Small to Exist, But We Finally Know Their Secret - ScienceAlert

White dwarfs are what becomes of a star less than about eight times the mass of the Sun when it runs out of fuel for the process of nuclear fusion.

If something else – such as a binary companion – were to slurp mass off the white dwarf, that would speed the process significantly, neatly explaining the presence of ELMs in the Universe.

This is when a white dwarf is in a binary system with another star, so close together that the white dwarf is accreting material from its companion.

The balance can tip so that the other star starts stealing mass from the white dwarf instead.

"We found the evolutionary link between two classes of binary stars – cataclysmic variables and ELM white dwarfs – and we found a decent number of them.".

All of the white dwarfs showed signs of mass loss to their companion stars; for 13 of the stars, the process was still ongoing, while the remaining eight were no longer losing mass, but were puffy, as though mass loss was recent.