July 19, 2001 NASA PR: 01-146 The first unambiguous evidence for
a giant halo of hot gas around a nearby, spiral galaxy much like
our own Milky Way was found by astronomers using NASA's Chandra
X-ray Observatory. This discovery may lead to a better
understanding of our own Galaxy, as well the structure and
evolution of galaxies in general. A team of astronomers, led by
Professor Daniel Wang of the University of Massachusetts,
Amherst, observed NGC 4631, a spiral galaxy approximately 25
million light years from Earth with both Chandra and NASA's
Hubble Space Telescope. While previous X-ray satellites have
detected extended X-ray emission from this and other spiral
galaxies, because of Chandra's exceptional resolution this is
the first time that astronomers were able to separate the
individual X-ray sources from the diffuse halo. Chandra found
the diffuse halo of X-ray gas to be radiating at a temperature
of almost 3 million degrees and extending some 25,000 light
years from the galactic plane. "Scientists have