Jul 19 2001
From The Space Library
Daniel Wang, a University of Massachusetts professor and leader of a study team of astronomers, announced that his team had discovered a giant halo of hot gas spiraling a galaxy similar to the Milky Way and relatively near Earth. The researchers had used the Chandra X-ray Observatory and the HST to observe galaxy NGC 4631, some 25 million light-years from Earth. The discovery not only revealed the increasing power of the astronomical tools at the disposal of scientists, but also contributed to astronomers’ knowledge about the structure and evolution of galaxies. Wang explained the significance of the discovery: “Scientists have debated for over 40 years whether the Milky Way has an extended corona, or halo, of hot gas . . . by studying similar galaxies like NGC 4631, we can get an idea of what’s going on within our own galaxy.” The study’s results also provided new information about how energy and mass spin around galaxies, as well as about the possible effects of rapid star formation. (NASA, “Chandra Detects Halo of Hot Gas Around Milky Way–Like Galaxy,” news release 01-146, 19 July 2001.)
Arthur F. Davidsen, an astrophysicist who had helped found the Space Telescope Science Institute at Johns Hopkins University in Baltimore, Maryland, died at age 57. Davidsen had served for many years as a professor of physics and astronomy at Johns Hopkins, focusing much of his research on the missing mass or dark matter of the universe. His findings had led to the development of the theory that, because of the reflecting light of other bodies, we are able to observe only about 1 percent of the universe’s matter. Davidsen’s work indicated that, although the remaining matter exists, it remains hidden from us. Not only had Davidsen led his colleagues in establishing the Space Telescope Science Institute, but he had also encouraged the Institute to participate in operating the HST. In his later years, Davidsen had even begun planning for the instrument that would eventually supplant the HST as the world’s foremost astronomical tool. Davidsen had trained at Princeton University and at the University of California at Berkeley. In 1979 he had won the American Astronomical Society’s Helen B. Warner Prize for his work using a rocket to obtain the first ultraviolet spectrum of a quasar. (Martin Weil, “Hopkins Astrophysicist Arthur Davidsen Dies,” Washington Post, 22 July 2001; Los Angeles Times, “Obituaries: Arthur Davidsen; Astrophysicist Led Work To Build Knowledge of Universe,” 23 July 2001.)
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