Neutron stars are the dead cores of massive stars that collapsed and exploded. They are considered the densest object in the universe after black holes and got their name because they harbor extremely strong gravity. Electrons and protons collapse in their atoms, forming neutrons. They even have a greater mass than the Sun.

Astrophysicists have used a new neutron star model to map the tiny raised areas on neutron stars, which are otherwise perfectly spherical, Gizmodo reported. The team found that these tiny mountains were extremely small, that even the highest mountain is only less than a millimeter tall because of the intense gravitational pull.

 Neutron Stars Have Tiny Mountains That Are No More Than Millimeters Tall, Study Suggests
(Photo: Wikimedia Commons)
Artist's illustration of an 'isolated neutron star' -- one without associated supernova remnants, binary companions, or radio pulsations.

Mountains on Neutron Stars

The team of astrophysicists published their findings in two papers that are currently hosted in the pre-print server arXriv. These papers assess the size of neutron star mountains, which will be presented to the Royal Astronomical Society's National Astronomy Meeting.

"For the past two decades, there has been much interest in understanding how large these mountains can be before the crust of the neutron star breaks, and the mountain can no longer be supported," astrophysicist Fabian Gittins from the University of Southampton and lead author of the two papers said in a Royal Astronomical Society press release.

However, previous studies showed that neutron star mountains could be as large as few centimeters, promoting deviation from a perfectly spherical shape of a neutron star. Nils Andersson, the co-author on both papers and an astrophysicist from the University of Southampton, said that these mountains appear too large in previous studies because previous models assumed the strain is maximal at all points at the same time.

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What Do Mountains in Neutron Stars Imply?

Neutron stars were formed when massive stars run out of fuel to power nuclear fusion, which means that the force that balances the gravity's inward pull is stopped that leads to gravitational collapse of the star and creates supernova explosions leaving only its dense core.

Neutron stars are protected from the supernova collapse and, in turn, become black holes due to the quantum mechanical properties of the neutrons inside them.

The findings of the study are a result of a computer model of neutron stars that simulated a realistic neutron star and the forces acting upon it. It showed how well neutron stars could support deviations from being perfectly spherical without their crust being strained to the point that it breaks.

This revealed how mountains could be formed on the remnants of stars and how such formations would only be a millimeter tall or less, ZME Science reported. Gittins added that the formation of neutron star mountains suggests that observing gravitational forces on neutron stars could be even more challenging than what previous scientists believed.

The study may have implications beyond the modeling of neutron stars, such as the pulsars of the tiny deformations on the surface of the rapidly spinning neutron that has been predicted by the general relativity theory and detected on Earth.

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Check out more news and information on Neutron Stars in Science Times.