However, as noted by the arXiv blog, there's a catch. The neutron star's nucleons can only be forced into cubes when the density is very high. Only when the neutron star has a mass of close to two solar masses (the maximum theoretical neutron star mass allowed) will its nucleons take on cube-like qualities.
Larger-mass neutron stars aren't thought to exist as the gravitational force will be too powerful for degenerate matter to maintain its structure. In other words, the neutron star would collapse and form a black hole.
Although there are hypothetical objects - known as "quark stars" or "strange stars" - predicted to be more massive, creating an intermediate stage between neutron star and black hole, there is little observational evidence that they exist.
So, is there a class of neutron star that has a mass close to two suns, below the threshold of gravitational collapse? Actually, there is.
Discovered last year, PSR J1614-2230 is a millisecond pulsar orbiting with a white dwarf binary buddy. Pulsars are spinning neutron stars that emit beams of electromagnetic radiation from their poles. As the pulsar rotates, we see a flash. In the case of PSR J1614-2230, it flashes at a rate of 317 times per second - it therefore spins at a breakneck speed of 317 times per second.
But that's not what makes PSR J1614-2230 special, it's the fact that its mass has been calculated at 1.97 solar masses - it is the most massive neutron star ever observed.
Although it's a long shot to think we might be able to measure PSR J1614-2230 so exactly to reveal the structure of the neutrons on a quantum level, the neutron star's observational characteristics may seem slightly more exotic than "usual." If it has a cubic neutron structure, its density will be higher, affecting its spin and composition.
It will be interesting to see if PSR J1614-2230, or other objects close to its mass, behave differently. In which case, astronomers may be looking at entirely different state of exotic matter.
Source: arXiv blog
Image credits: ESO/Luís Calçada (top), Felipe Llanes-Estrada/Gaspar Moreno Navarro (middle)