Technology.am (May 10, 2009) —A theoretical physicist at Indiana University shows that the crusts of neutron stars are 10 billion times stronger than steel or any other of the earth’s strongest metal alloys.
Charles Horowitz, a professor in the Indiana University came to the conclusion after large-scale molecular dynamics computer simulations were conducted at Indiana University and Los Alamos National Laboratory in New Mexico. The simulations identified a neutron star crust that far exceeded the strength of any material known on earth.
Exhibiting extreme gravity while rotating as fast as 700 times per second, neutron stars are massive stars that collapsed once their cores ceased nuclear fusion and energy production. The only things more dense are black holes, as a teaspoonful of neutron star matter would weigh about 100 million tons.
Scientists want to understand the structure of neutron stars, in part, because surface irregularities, or mountains, in the crust could radiate gravitational waves and in turn may create ripples in space-time. Understanding how high a mountain might become before collapsing from the neutron star’s gravity, or estimating the crust’s breaking strain, also has implications for better understanding star quakes or magnetar giant flares.
Horowitz said, “We modeled a small region of the neutron star crust by following the individual motions of up to 12 million particles, we then calculated how the crust deforms and eventually breaks under the extreme weight of a neutron star mountain.”
The crust could be so strong as to be able to elicit gravitational waves that could not only limit the spin periods of some stars, but that could also be detected by high-resolution telescopes called interferometers, the modeling found.
Horowitz said, “The maximum possible size of these mountains depends on the breaking strain of the neutron star crust, the large breaking strain that we find should support mountains on rapidly rotating neutron stars large enough to efficiently radiate gravitational waves.”
Because of the intense pressure found on neutron stars, structural flaws and impurities that weaken things like rocks and steel are less likely to strain the crystals that form during the nucleosynthesis that occurs to form neutron star crust. Squeezed together by gravitational force, the crust can withstand a breaking strain 10 billion times the pressure it would take to snap steel.