ASHINGTON, Jan. 9
— Peering deep into the heart of the Milky Way with X-ray vision, an
American spacecraft has produced what astronomers say is the
sharpest-ever image of the most dynamic region of Earth's home
A team of astronomers led by Dr. Q. Daniel Wang of the University
of Massachusetts at Amherst reported here today that NASA's
Earth-orbiting Chandra X-ray Observatory had detected more than
1,000 discrete sources of the powerful X-rays, far more than the
dozen sources previously known.
"This is an important step toward understanding the most active
region of our galaxy," Dr. Wang said at a meeting of the American
Astronomical Society. "It gives us a new perspective of the
interplay of stars, gas, dust and gravity at the very epicenter of
Until the advent of X-ray spacecraft, especially Chandra, a
detailed examination of the Milky Way's core had been impossible,
since most of it is obscured in a smog of gas and dust. By
penetrating this smog, scientists said, the new research could lead
to insights into what is happening at the centers of other
The Chandra images cover a region 400 light years wide by 900
light years long, in the galactic suburbs some 20,000 light years
away from the Sun. Looking at the glittering arc of the Milky Way in
the summer from the Northern Hemisphere, its center would be close
to the southern horizon. The best view at all times is from the
But the X-ray images reveal phenomena unseen in other
wavelengths, even by the most powerful ground-based telescopes.
In their analysis, Dr. Wang and his colleagues — Dr. Cornelia
Lang, also of the University of Massachusetts, and Dr. Eric Gotthelf
of Columbia University — determined that most of the discrete X-ray
sources were from remnants of dead stars, like white dwarfs, neutron
stars and black holes.
The more diffuse X-ray emissions in the region, the astronomers
said, had lower energies and seemed to come from gases not as hot as
once thought, a relatively mild 10 million degrees. Their source
appeared to be the titanic turbulence all around.
Stars are forming there at a much more rapid rate than elsewhere
in the galaxy. And stars are exploding more frequently than
elsewhere, the supernovas emitting tremendous shock waves and a
blizzard of debris.
"It's a great image," said Dr. Farhad Yusef-Zadeh, an astronomer
at Northwestern University.
But noting that other scientists suspected that the collisions of
low- energy cosmic rays could also be responsible for the
radiations, Dr. Yusef-Zadeh added that "the origin of the hot gas
remained a mystery."
For another view of the Milky Way, Dr. Michael Skrutskie of the
University of Virginia reported using infrared data from 30,000
stars to trace the outlines of the galaxy's complete disk. He called
it the first- ever bird's-eye view of the