More on black holes.

More on black holes

With all four of Astro's telescopes sometimes trained on the same star or galaxy, scientists had a unique opportunity to conduct collaborative research on the heavens. For example, both the Hopkins Ultraviolet Telescope and the Broad Band X-ray Telescope recorded spectra from the cores of several quasars and Seyfert galaxies. Tracing the intensity of X-ray and ultraviolet light and comparing the resulting curve to theoretical predictions may provide the best indication yet of whether a black hole powers the enormous energy output at the centers of these objects (SN: 12/15/90, p.372).

Simultaneous measurements from the Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE) indicated the shape of material that produces some of these intense emissions as well as the density of its immediate surroundings. Preliminary analysis of ultraviolet observations of the Seyfert galaxy NGC 1068, believed to harbor a black hole, shows that a significant amount of the light is polarized (waves aligned in one direction). The finding, says Christopher M. Anderson of the \niversity of Wisconsin-Madison, agrees with a widely accepted model in which a disk of captured matter spews out a stream of intense energy as its mass disappears into the gravitational clutches of a black hole. A surrounding cloud of charged particles generated by the black hole polarizes the light. No net polarization could be detected if the mass fell in uniformly from all directions, rather than from an encircling disk, Anderson says.