X-ray of Milky Way shows fluttering heart

The chaotic center of the Milky Way

WASHINGTON (Reuters) -- A new panoramic X-ray image of the Milky Way galaxy reveals a turbulent center teeming with 1,000 sources of high energy that might be dying stars or black holes, astronomers reported Wednesday.

The mosaic image is made up of 30 separate pictures made by the Chandra X-Ray Observatory, which monitors space through X-rays that filter out the cosmic dust that can obscure images made with optical devices.

It shows bursts of brilliant green and red and small pinpoints of blue at the galactic center, which one researcher likened to the lights of a big city on Earth.

"We all know we live in the Milky Way, which is a big city of stars. As for the center of the 'city,' what happens there matters, for the evolution of our galaxy," said astronomer David Wang of the University of Massachusetts.

Wang noted that the galactic center used to be hard for scientists to study because of the space dust and gas that has blocked the view. Earlier observations showed about a dozen high-energy sources in the center of the galaxy, he told reporters at a meeting of the American Astronomical Society in Washington.

Showing an image of the central region taken by an earlier instrument, Wang noted it showed only "some blobs of X-ray emission."

Then, unveiling the new mosaic, Wang said, "Because of the high resolution of Chandra, we now detect about 1,000 X-ray sources, compared to about a dozen sources previously known."

Black holes, white dwarfs

The Chandra image shows just the center of the Milky Way, but that is vast enough: an area about 400 light-years by 900 light-years. A light-year is about 6 trillion miles, the distance light travels in a year.

After analyzing some of the objects in the new picture, Wang said he and his colleagues think many of these X-ray sources are black holes, white dwarfs -- Earth-size remnants of burned-out sun-like stars -- and neutron stars, the remains of exploded massive stars.

"This tells us a great deal about the turbulent nature of the central region of our galaxy and also gives you a new perspective on the interplay between all its various components: stars, gas, dust, magnetic fields and gravity of our galaxy," Wang said.

Study of the new Chandra data allowed scientists to separate the individual X-ray sources from the diffuse glow produced by hot gas at the galaxy's center. Wang and his colleagues found that the individual sources, and not the hot gas, produced most of the X-rays of this region.

The diffuse X-ray emission seems to be related to intense action at the heart of the Milky Way, where stars are being born and dying at a must faster pace than in the more placid galactic "suburbs," the researchers said in a statement.

"The galactic center is dominated by very high pressures due to the hot gas component and the strong magnetic fields," Cornelia Lang, also of the University of Massachusetts, said.

"It's a nice place to visit with a telescope but I wouldn't want to live there."

The scientists' research will be published in Thursday's issue of the journal Nature.

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