The X-ray spectrum
The X-ray spectrum (see inset) of a binary star system consisting of a black hole and a normal star indicates that turbulent winds of multimillion degree gas are swirling around the black hole. As the illustration shows, much of the hot gas is spiralling inward toward the black hole, but about 30% is blowing away. (Illustration: NASA/CXC/M.Weiss; X-ray Spectrum: NASA/CXC/U.Michigan/J Miller et al.)