The tallest mountains on a neutron star are only millimeters high

Here on Earth, mountains get extremely tall, thousands and thousands of feet high. However, new models of neutron stars show that the tallest mountains on these objects are only fractions of millimeters high due to the massive gravity of the incredibly dense objects. Neutron stars are some of the densest objects in the known universe, weighing about as much as the sun while being only about 10 kilometers across.

Because the stars are so densely packed, they have massive gravitational pull estimated at a billion times stronger than Earth's gravitational pull. The immense gravity squishes every feature on the surface of the star to extremely small dimensions. With all of its surface features smoothed out by immense gravity, the stellar remnant is an almost perfect sphere.

While the "mountains" on the neutron star's surface are billions of times smaller than similar features on Earth, they are nonetheless known as mountains. Researchers used computational modeling to build realistic neutron stars and then subjected them to a range of mathematical forces to find how mountains on the neutron star were created.

In their study, the team investigated the role ultra-dense nuclear matter played in supporting the mountains and found that the largest mountains produced are only a fraction of a millimeter tall. That is 100 times smaller than previously estimated. Researchers say over the past 20 years, interest in scientific communities has been high in understanding how large mountains on the neutron stars could be before the crust of the star breaks and the mountain can no longer be supported.

Previous work suggested that neutron stars could sustain deviations from a perfect sphere of up to a few parts in one million. That would've implied mountains as large as a few centimeters. However, the calculations assumed the neutron star was strained in a way that the crust was close to breaking at every point, but new models indicate those conditions aren't realistic.