When asteroids travel too close to white dwarfs, the dense remnants of stars that have exhausted their nuclear fuel, powerful gravitational forces can tear them apart. However, new research from Planetary Science Institute (PSI) suggests that these asteroids don’t immediately break into dust. Instead, most of the mass initially remains in larger fragments, revealing a previously overlooked step in how debris forms around dying stars.

The study, led by PSI senior scientist Jordan Steckloff, identifies a “kilometer-size barrier” that limits just how much asteroids can break apart when subjected to the powerful gravitational forces of white dwarfs.

White dwarfs are often surrounded by disks of planetary debris, including dust from asteroids and other objects pulled apart by the star’s gravity. Previous models have generally assumed that these objects behave like loosely bound piles of rubble with no internal strength. This allows them to break into increasingly smaller pieces and eventually turn into dust.