"The sharpest image of the most active region in the Milky Way galaxy"
John Noble Wilford, New York Times
Photo: NASA A mosaic of images taken by the Chandra Observatory, encompassing a region of the Milky Way that is 900 light-years long and 400 light-years wide
Peering into the heart of the Milky Way, using X-ray-sensitive telescopes, a US spacecraft has produced what astronomers say is the sharpest image ever taken of the most dynamic region of Earth's home galaxy.
A team of astronomers, led by Dr. Daniel Wang from the University of Massachusetts at Amherst, reported late last week that NASA's X-ray space telescope, "Chandra", discovered more than a thousand discrete sources (separate from each other) of X-rays strong. Until now about a dozen such sources were known.
"This is an important step toward understanding the most active region of our galaxy," said Dr. Wang at a meeting of the American Astronomical Society. "This gives us a new perspective on the interrelationships of the stars, gases, dust and gravity at the heart of the galaxy."
Until the development of space telescopes sensitive to X-rays and especially the Chandra observatory, it was not possible to examine the center of the Milky Way in detail because most of it is hidden in a fog of gas and dust. According to the researchers, the penetration into this nebula may lead to new insights into what is happening in the centers of other galaxies.
The X-ray images reveal phenomena that are not visible at other wavelengths, even with the largest ground-based telescopes. Analyzing the images, Dr. Wang and his colleagues - Dr. Cornelia Lang from the University of Massachusetts and Dr. Eric Gottlief from Columbia University - determined that most of the sources of the discrete X-rays are the remains of dead stars - white dwarfs, neutron stars and black holes.
In addition to radiation from discrete sources, diffuse X-ray emission was also picked up, which seems to originate from strong eddies occurring all over the region. This radiation is less energetic than the radiation that comes from discrete sources, and astronomers believe that it comes from gases that are not as hot as they thought until now - their temperature is only about 10 million degrees.
Stars form in this region at a much faster rate than elsewhere in the galaxy. Stars also explode much more often than elsewhere.
Another view of the Milky Way is provided by Dr. Michael Skrotsky of the University of Virginia, who reported at the Astronomical Society's convention that he used data from observations in the fields of infrared radiation emitted by 30 stars to discover the outlines of the entire disk of the galaxy. He called it "the first bird's eye view of the galaxy".
New York Times
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