  When a star exhausts its nuclear fuel, it either explodes as a supernova or
more quiescently becomes a white dwarf, an object about half the mass of our
Sun with a radius of about that of the Earth. About one fifth of white dwarfs
exhibit the presence of magnetic fields, whose origin has long been debated as
either the product of previous stages of evolution or of binary interactions.
We here report the discovery of two massive and magnetic white dwarf members of
young star clusters in the Gaia DR2 database, while a third massive and
magnetic cluster white dwarf was already reported in a previous paper. These
stars are most likely the product of single-star evolution and therefore
challenge the merger scenario as the only way to produce magnetic white dwarfs.
The progenitor masses of these stars are all above 5 solar masses, and there
are only two other cluster white dwarfs whose distances have been unambiguously
measured with Gaia and whose progenitors' masses fall in this range. This high
incidence of magnetic white dwarfs indicates that intermediate-mass progenitors
are more likely to produce magnetic remnants and that a fraction of magnetic
white dwarfs forms from intermediate-mass stars.
