May 11, 2009

Neutron star crusts: Stronger than steel

U.S. physicists say they've determined the crusts of neutron stars are 10 billion times stronger than steel or any other metal alloy found on Earth.

The scientists said a neutron star is a star that collapsed when its core ceased nuclear fusion. Exhibiting extreme gravity while rotating as fast as 700 times per second, a teaspoonful of neutron star matter would weight about 100 million tons, the researchers said.

Indiana University Professor Charles Horowitz and colleagues conducted large-scale molecular dynamics computer simulations at the university and Los Alamos National Laboratory in New Mexico to reach their conclusion.

We modeled a small region of the neutron star crust by following the individual motions of up to 12 million particles, Horowitz said. We then calculated how the crust deforms and eventually breaks under the extreme weight of a neutron star mountain.

The work, performed on a large computer cluster at the national laboratory, identified a neutron star crust that far exceeded the strength of any material known on Earth.

Horowitz said 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 research appears in the journal Physical Review Letters.