Why are neutron stars called soft?

The remnants of the nuclei of stars that exploded in supernovae called neutron stars are one of the densest materials in the universe. In them, twice as incredibly small as the sun, two dozen kilometers in diameter, can fill the city.

Due to the extreme gravity of the surface of neutron stars, Thin crust of hydrogen and helium, Is incredibly smooth, although minor distortions can be seen due to stellar activity. New modeling shows that these distortions are at least 100 times smaller than expected.

“Neutron stars are incredibly round objects,” says Fabian Kittins of the University of Southampton in the United Kingdom. “It’s very interesting.”

Kittins and colleagues modeled the various forces acting on a neutron star and found that any surface irregularities could be less than 0.1 mm in height, otherwise the surface would shrink.

NASA / Wikimedia Commons artwork / neutron star system

“We found a lot of misconceptions,” Kittins says. “Previous work has given the stars a physically impossible shape.”

Astronomers have suggested that changes in the surface of neutron stars may distort enough time to detect induced gravitational waves, but this latest work suggests that they are much harder to detect than they expected.

Like the Einstein underground telescope proposed in Europe, “we can only do this with third-generation gravitational wave inventors,” says Kittins.