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Binary Neutron Star Collision
David Bock (NCSA Visualization and Virtual Environments Group)
Video: 2 MB, MPEG
Neutron stars are the cinders left over from a supernova explosion. At the instant of their creation, half a million Earth masses of matter are crushed into a ball just ten miles across; one teaspoonful of neutron star material weighs five billion tons. In rare instances, two neutron stars can orbit around each other in a binary system, releasing energy in the form of gravitational radiation. After millions of years, they spiral toward each other, moving faster and faster until they produce a crash so violent that the resulting explosion can be seen billions of light years away.
What happens during the collision?
This movie shows the results of a supercomputer simulation of what might happen when two neutron stars in a binary system collide. By the time they hit each other, they're traveling at nearly the speed of light, and orbit each other a thousand times a second. According to the calculations, the two neutron stars merge together in less than a hundredth of a second and release more energy during that time than our Sun would in ten billion years!
Gordon Myers
Tags:
Stellar Collisions in Globular Clusters
Aaron Warren (Rutgers University), James Lombardi (Vassar College)
Globular clusters are spherically distributed balls
of hundreds of thousands of stars. The stars all formed in the cluster at about the same epoch. The clusters orbit large galaxies, such as our own Milky Way, and are generally the densest collections of stars in the cosmos. Each globular cluster has an upper limit to how massive its stars can be, called the turn-off mass.
But sometimes abnormally hot stars called blue stragglers
are found in them, which are higher than the turn-off mass. How do they get there? Could a collision between two older, smaller stars create these larger, younger blue stragglers?
Video: 4 MB, MPEG
Star formation in globular clusters
This movie shows the result of what happens when two stars in a globular cluster collide. The stars originally have masses of 0.6 and 0.8 times the mass of our sun. The images that compose the simulations are generated by taking a two-dimensional slice in the equatorial plane of the three-dimensional simulation. The colors represents different densities: dark red corresponds to low density regions while the bright yellow corresponds to a high density region. According to this calculation, it is indeed possible that these small stars can join together without being destroyed, breathing new life into an old cluster. Apparently, if you smash old, dim stars, you just might end up with a young, bright star—a blue straggler!
Gordon Myers
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