N. Rijal

A neutron star is the dead core of a star that once exploded, compressed to the size of a city. If a normal star is nearby, the neutron star siphons matter from it like a vacuum cleaner. This matter falls onto the surface and forms a crust — a solid layer of neutron-rich atomic nuclei.

In an atomic nucleus, it's usually crowded: protons and neutrons are packed like commuters on a rush-hour train. But beryllium-11 is different. One neutron keeps its distance from the rest, forming a diffuse cloud — a nuclear halo. This nucleus resembles a planet with a satellite on a highly elongated orbit.