Steve Roy

Marshall Space Flight Center

Huntsville, AL

Phone: 256-544-6535

Deborah Halber

Massachusetts Institute of Technology

Cambridge, MA

Phone: 617-258-9276

Dr. Wallace Tucker

Chandra X-ray Observatory Center

Harvard-Smithsonian Center for Astrophysics

Cambridge, MA

Phone: 617-496-7998

CXC PR: 00-05

Chandra Finds Oxygen and Neon Ring in Ashes of Exploded Star

NASA’s Chandra X-ray Observatory has revealed an expanding ring-like structure of oxygen and neon
that was hurled into space by the explosion of a massive star. The image of E0102-72 provides
unprecedented details about the creation and dispersal of heavy elements necessary to form planets like

The results were reported by Professor Claude Canizares of the
Massachusetts Institute of Technology (MIT), Cambridge, at the 195th national meeting of the American
Astronomical Society in Atlanta, Ga. Drs. Kathryn Flanagan, David Davis, and John Houck of MIT
collaborated with Canizares in this investigation.

E0102-72 is the remnant of a supernova explosion located in our neighbor galaxy, the Small Magellanic
Cloud, nearly 200,000 light years away. It was created by the explosion of a star that was more than
ten times as massive as our Sun. We are seeing the aftermath of the explosion a thousand or more
years after the outburst. Shock waves are heating gas to temperatures of nearly 10 million degrees, so
it glows with X-rays that are detected by Chandra’s instruments.

By using the High Energy Transmission Grating Spectrometer (HETG), astronomers were able to pinpoint
the distribution of each chemical element individually and measure the velocities of different parts of the
expanding ring. They also show the shock wave in a kind of “freeze- frame,” revealing the progressive
heating of the stellar matter as it plows into the surrounding gas. This is the first time such detailed
X-ray information has ever been obtained for a supernova remnant, and should provide critical clues to
the nature of supernovae.

The grating spectrometer, which was built by an MIT team led by
Canizares, spreads the X-rays according to their wavelength, giving distinct images of the object at
specific wavelengths characteristic of each chemical element. Small wavelength shifts caused by the
Doppler effect are used to measure the expansion velocities of each element independently.

“We’ve been studying these supernova remnants for decades, but now we’re getting the kind of
information we need to really test the theories,” said Canizares.

“Understanding supernovae helps us to learn about the processes that formed chemical elements like
those which are found on Earth and are necessary for life,” said Flanagan.

Most of the oxygen in the universe, for example, is synthesized in the interiors of relatively few massive
stars like the one being studied here. When they explode, they expel the newly manufactured elements
which become part of the raw material for new stars and planets. The amount of oxygen in the
E0102-72 ring is enough for thousands of solar systems.

By measuring the expansion velocity of the ring, the team can estimate the amount of energy liberated in
the explosion. The expansion energy would be enough to power the sun for 3 billion years. The ring has
more complex structure and motion than can be explained by current simplified theories, suggesting
complexity in the explosion itself or in the surrounding interstellar matter.

The supernova remnant also provides a laboratory for atomic physics. The observations show how the
atoms in the expelled matter behave when heated to such high temperatures. The images reveal the
progressive stripping of electrons from the atoms after the
super-sonic shock wave has passed.

The Chandra observation was taken using the HETG in conjunction
with the Advanced CCD Imaging Spectrometer (ACIS) on September
28 and October 10, 1999. ACIS was built by Pennsylvania State
University, University Park, and the Massachusetts Institute of
Technology, Cambridge.

To follow Chandra’s progress or download images visit the Chandra sites at


NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. TRW, Inc.,
Redondo Beach, Calif., is the prime contractor for the spacecraft. The Smithsonian’s Chandra X-ray
Center controls science and flight operations from Cambridge, Mass.

High resolution digital versions of the X-ray image (JPG, 300 dpi TIFF ) and other information associated
with this release are available on the Internet at:

Further information on the HETG may be found at:


Chandra Image of Oxygen Ring in E0102-72

This X-ray image of the supernova remnant E0102-72 shows an expanding multimillion degree ring of
oxygen that was created deep inside a massive star and hurled into space by the explosion of the star.
The ring is about 30 light years across and contains enough oxygen for thousands of solar systems.
Images such as these provide unprecedented details about the creation and dispersal of heavy elements
necessary to form planets like Earth. E0102-72 is in the Small Magellanic Cloud a small galaxy about
200,000 light years from Earth.

Chandra X-ray Observatory ACIS/High Energy Transmission Grating Image