Scientists have discovered a new key to better understand the bizarre activities of neutron stars. They pack the mass multiple suns into a space tinier than a city.

It so happens that a trio of properties which explains how fast the star spins and how easily its shape deforms are universally related and linked. Because of this, astronomers can now better understand the physics inside neuron stars’ cores and determine these stars from quark stars, their even uncanny cousins.

When enormous stars run out of fuel for nuclear fusion and collide, they oust their outer layers, and their cores fall inward under the pull of gravity to become denser and denser, creating Nuclear Stars. Quark stars, on the other hand, are odd objects. They are even denser, where neutrons can’t survive and they melt down into their constituent quarks.

“Quark stars haven't been observed," said Nicolas Yunes, a physicist at Montana State University who co-authored the new study with his Montana State colleague Kent Yagi.

Scientists can’t exactly differentiate neutron stars and quark stars from current observations. However, the new findings by Yagi and Yunes could help discern the two super-dense bodies.

It has been discovered that there is a relationship between three quantities in all neutron stars:
• A star’s moment of inertia
• Love number
• Quadrupolemoment, which reflects how star’s shape easily deforms.

And if one of these quantities can be measured, the others can be deduced.

Scientists didn’t realize that this relationship known for black holes, which are even denser than quark stars, is true and applicable to others.

“For black holes there is a well-known definite relation, but that made sense because black holes don’t have internal structure. We all expected that that wouldn’t be true once you have objects that do have structure,” Yunes to

Better understanding of this relationship for neutron stars can aid scientists in their study of general relativity and the laws of physics in a strong gravitational field.

Yagi, via e-mail, noted, “Since a neutron star is very compact, it offers us a nice test-bed to probe gravitational theory in the strong-field regime. Previously, uncertainties about the internal structure of neutron stars prevented researchers from carrying out such tests. However, since our universal relations do not depend on the neutron star internal structure, one can perform general relativity tests without being affected by the ignorance of the internal structure.

The study was published in the July 25 issue of the online journal Science.