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Observation of the Week!

July 3, 1996

Surfing at Half the Speed of Light!

The Crab Pulsar
Image Credits: Jeff Hester and Paul Scowen, Arizona State University/NASA (left image); Paul Scowen, Arizona State University (right image)

Imagine surfing on waves moving at half the speed of light. Waves traveling this fast are being shown in the set of three black and white images of the center of the Crab Nebula. The nebula (right image) is the gaseous remnant of a supernova explosion that was observed nearly one thousand years ago and recorded by Chinese astronomers.

The set of three images was taken over a period of several months and shows the spreading of wispy looking waves through the inner region of the nebula. The difference between these waves and, for example, ocean waves, on which you can surf, is that the Crab Nebula is 10 light-years across and lies at a distance of 7,000 light-years from earth. The waves are spreading at half the speed of light. Astronomers have never seen wave motions such as these before.

At the center of the Crab Nebula lies a small, supercompact star made mostly of neutrons. It is the collapsed core of the star that gave rise to the supernova explosion. Everything about this stellar remnant is extreme. It is only about a dozen miles across, but has more mass than the sun. A tablespoon of the star's matter would weigh more than a billion tons! It possesses intense magnetic fields and spins 30 times per second. Synchronized with this spinning are pulses of light that we observe at a rate of 30 per second. For that reason, the star is called the Crab Pulsar.

As the pulsar spins, its magnetic fields act like a slingshot, hurling electrons and other charged particles outward into the nebula at speeds close to that of light. It is these particles that power the waves seen in the above images.

The black and white images were taken with NASA's Hubble Space Telescope by Jeff Hester and Paul Scowen. The color image is a composite of pictures taken with the Mount Palomar 60-inch telescope.

More Cool Stuff

The above black and white images of wave motion in the Crab Nebula come from a May 30, 1996, press release of the Space Telescope Science Institute (STScI):
http://www.stsci.edu/pubinfo/PR/96/22/B.html
For a movie of the waves in the Crab Nebula and animation of the environment around the Crab Pulsar, go to a second page of the STScI:
http://www.stsci.edu/pubinfo/PR/96/22.html
The color image of the Crab Nebula came from a page of the University of Arizona chapter of the Students for the Exploration and Development of Space (SEDS):
http://seds.lpl.arizona.edu/messier/more/m001_p2.html
For a second image of the Crab Nebula, go to another page of the SEDS site:
http://seds.lpl.arizona.edu/messier/more/m001_palo.html
Check out the homepage of the Mt. Palomar Observatory:
http://astro.caltech.edu/observatories/palomar

Check out other observations in the Observation of the Week Archive.



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