Sep 21, 1999

New Chandra Images Released

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X-ray pictures from NASA's Chandra X-ray Observatory reveal previously unobserved features in the remnants of three different supernova explosions.




Sept. 21, 1999: Images released yesterday from NASA's Chandra X-ray Observatory reveal previously unobserved features in the remnants of three different supernova explosions. Two of the objects, G21.5-0.9 and PSR 0540-69, show details of the prodigious production of energetic particles by a rapidly rotating, highly magnetized neutron star, as well as the enormous shell structures produced by the explosions. The image of the third remnant, E0102-72, reveals puzzling spoke-like structures in its interior.


Right: Chandra's image of supernova remnant G21.5-0.9. At both radio and x-ray wavelengths, this relic of a supernova blast appears as a round patch in the sky. Detailed observations with radio telescopes confirm that the radio waves are produced by high energy electrons spiraling around magnetic field lines (synchrotron radiation). The x-rays are probably produced by the same process, but the electrons involved have energies many thousands times higher than those that produce the radio waves. [more]



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G21.5-0.9, in the constellation of Scutum, is about 16,000 light years from Earth. One light year equals six trillion miles. Chandra's image shows a bright nebula surrounded by a much larger diffuse cloud.

Inside the inner nebula is a bright central source that is thought to be a rapidly rotating, highly magnetized neutron star. A rotating neutron star acts like a powerful generator, creating intense electric voltages that accelerate electrons to speeds close to the velocity of light. The total output of this generator is greater than a thousand suns. The fluffy appearance of the central nebula is thought to be due to magnetic field lines which constrain the motions of the high energy electrons.

"It's a remarkable image," said Dr. Patrick Slane of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "Neither the inner core nor the outer shell has ever been seen before."

"It is as though we have a set of Russian dolls, with structures embedded within structures," said Professor Gordon Garmire of Pennsylvania State University in University Park, Pa., and principal investigator of Chandra's Charge-Coupled Device X-ray camera, used to make the image.

NASA's project scientist, Dr. Martin Weisskopf of the Marshall Space Flight Center in Huntsville, Ala., said, "Chandra's capability to provide surprises and insights continues!"
The existence of a rotating neutron star, or pulsar, in the center of G21.5-0.9 is inferred from the appearance of the nebula and the energy distribution of X-rays and radio waves from the nebula. This distribution, called non-thermal radiation, is characteristic of radiation produced by high energy electrons in a magnetic field.

Left: The bright spot in this new image from Chandra is the neutron star PSR 0540-69. This pulsar rotates very rapidly, making a complete rotation every one-twentieth of a second. It is similar in many ways to the famous Crab Nebula pulsar. [more info]

A previously known pulsar is observed directly in the Chandra image of PSR 0540-69. This pulsar, located in a 180,000 light-year-distant satellite galaxy to our Milky Way, emits pulses of radio, optical and X -ray energy at a rate of 50 per second. These pulses, which come from a neutron star rotating at this incredible rate, comprise only a few percent of the total energy output of the neutron star powerhouse.

"The Chandra image gives us a much better idea of how this energy source works," said Dr. Stephen Murray, principal investigator for the High Resolution Camera, the X-ray camera used to make this image. "You can see X-ray jets blasting out from the pulsar in both directions."

The third Chandra image is of E0102-72, in the Small Magellanic Cloud, another satellite galaxy of the Milky Way. This galaxy is 190,000 light years from Earth. This object, like G21.5-0.9 and PSR 0540-69, is believed to have resulted from the explosion of a massive star several thousand years ago. Stretching across 40 light years of space, the multi-million-degree source resembles a flaming cosmic wheel.

Right: E0102-72 is a supernova remnant in the Small Magellanic Cloud, a satellite galaxy of the Milky Way. This galaxy is 190,000 light years from Earth. E0102 -72, which is several thousand years old, is believed to have resulted from the explosion of a massive star. Stretching across forty light years of space, the multi-million degree source resembles a flaming cosmic wheel.

"Chandra's gallery of supernova remnants is giving us a lot to think about," said Dr. Fred Seward of Harvard-Smithsonian, who, with his colleagues, discovered E0102-72 and PSR 0540-69 by using a Chandra predecessor, NASA’s Einstein Observatory, over a decade ago. "We're seeing many things we thought should be there, and many others that we never expected. It's great!"



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To follow Chandra's progress, visit the Chandra News Web site at: and

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra X-ray Observatory for NASA's Office of Space Science, NASA Headquarters, Washington, D.C. The Smithsonian Astrophysical Observatory's Chandra X-ray Center in Cambridge, Mass., manages the Chandra science program and controls the observatory for NASA. TRW Space and Electronics Group of Redondo Beach, Calif., leads the contractor team that built Chandra.


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Chandra X-ray Observatory Center home page, with links to education, news, and technical pages.

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Chandra Project Science is managed at NASA/Marshall, has links to individual instruments and the prime contractor.

X-ray astrophysics branch at NASA/Marshall conducts a broad range of research and technology work, as well as supporting the Chandra X-ray Observatory.

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