A team led by astronomers at Columbia University have found the youngest pulsar yet, a hot, spinning, highly-magnetized infant no larger than Manhattan, born in a massive star explosion about 700 years ago. The pulsar possesses unusual properties that may force scientists to reconsider how pulsars are created and evolve.
Other known pulsars, in comparison, are thousands to millions of years old. This pulsar, in the supernova remnant Kes 75, is about 300 years younger than the second-youngest pulsar, the Crab, which scientists have long considered to be the archetypal young pulsar. Yet, compared to the Crab, the Kes 75 pulsar spins ten times more slowly; it is slowing down at a rate ten times faster; and it has a magnetic field that is ten times greater -- all unexpected findings that may cause scientists to rethink the birth properties and evolution of pulsars.
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These images are taken from a computer animation illustrating how rapidly rotating neutron stars (pulsars) produce regular flashes of light.
Neutron stars are created when a massive star explodes in a spectacularly violent event called a supernova. The core of the star collapses under its own weight while the outer layers are blown off. The core becomes the neutron star, and as it collapses, it spins much more rapidly than the original star because its diameter is a lot smaller. This is like what happens when skaters pull their outstretched arms in close to their bodies to spin faster. The collapse of the core concentrates its mass, about that of the Sun, into an extremely dense sphere the size of a large city. The collapse also concentrates the star's magnetic field; as a result, neutron stars have the most intense magnetic fields known in the Universe, up to trillions of times greater than the Earth's.
In the first picture (left), the sphere in the center represents the neutron star, and the surrounding lines emerging from the top and bottom of the sphere represent its magnetic field. The whirling magnetic field produced by the neutron star's rapid rotation accelerates electrically charged particles near the star. Their acceleration generates high-energy light, represented by the blue and white beams projecting from the star's magnetic poles.
In the second image (right), the light beam has rotated with the star and is now pointing directly at the viewer, resulting in a bright flash. The star acts like a celestial lighthouse, regularly producing pulses of light at its beams sweep past the Earth. Stars like these are called pulsars.
IMAGE CREDIT: NASA/Honeywell Max Q Digital Group, Dana Berry
http://imagine.gsfc.nasa.gov/docs/science/know_l1/pulsars.html
http://science.msfc.nasa.gov/newhome/headlines/mag_pix/xsection.jpg
http://heasarc.gsfc.nasa.gov/docs/xte/XTE.html
http://heasarc.gsfc.nasa.gov/docs/xte/learning_center/
http://universe.gsfc.nasa.gov/
