Thursday, May 01, 2008

NASA can now predict a neutron star explosion

Using observations from NASA’s Rossi X-ray Timing Explorer (RXTE), an international team of astronomers has discovered a timing mechanism that allows them to predict exactly when a superdense star will unleash incredibly powerful explosions. The bursts occur on a neutron star (the remnants of a collapsed super nova) which is often part of a binary pair. Hydrogen and helium gas from a companion star spirals onto the neutron star, slowly accumulating on its surface until it heats up to a critical temperature. Suddenly, the hydrogen and helium begin to fuse uncontrollably into heavier elements, igniting a thermonuclear flame that quickly spreads around the entire star. The resulting explosion appears as a bright flash of X-rays - releasing more energy in just 10 to 100 seconds than our Sun radiates in an entire week. Up until now, there has been no way to predict when the next explosion is likely to occur. The key to the discover lies in observations from the RXTE satellite, which can make extremely accurate timing measurements of x-ray emissions from neutron stars as they fuse gasses syphoned off their companion star. On the surface of the neutron star, these gasses fuse at very predictable periods. However as the the bursts of x-rays (which are given off each time hydrogen and helium atoms fuse into heavier elements ) slow down - scientist now know that an explosion is immanent.

No comments: