Tiny uranium crystals could cause massive explosions within a dead star, physicists suggest, which could lead to a cosmic version of a thermonuclear bomb.
Expired stars, called white dwarfs, slowly cool down as they get older. Heavy elements like uranium begin to crystallize and form “snowflakes” in the star cores. If enough uranium clumps together – around the mass of a grain of sand – this could trigger a chain of nuclear fission reactions or the fission of atomic nuclei.
These reactions could raise temperatures in the star, trigger nuclear fusion – the merging of atomic nuclei – and create a huge explosion that destroys the star, calculate two physicists in an article published on March 29 Physical Examination Letters. The effect is similar to a hydrogen bomb, a powerful thermonuclear weapon that causes fission reactions to trigger fusion, says Matt Caplan of Illinois State University in Normal. Caplan admits the scenario is still hypothetical – more research is needed to determine whether uranium snowflakes could really trigger a star detonation.
White dwarfs are already known to be explosive: they are the source of explosions known as type 1a supernovae. Typically, these explosions occur when a white dwarf extracts matter from a companion star (SN: 03/23/16). The researchers’ proposal for uranium snowflakes is an entirely new mechanism that could explain a small fraction of the Type 1a supernovae without the need for another star.