Learn about Cygnus X-1, an x-ray source that was the first widely accepted example of a black hole, in this media gallery featuring video from NOVA: Black Hole Apocalypse. The video describes how the advent of x-ray astronomy opened up a new world for astronomers to explore. Paul Murdin and colleagues discovered that Cygnus X-1 was likely a black hole by searching for signs of binary star systems, where one star was visible and the other an x-ray source. After analyzing data for a visible star that showed Doppler-shifted light, the researchers concluded that the mass of the x-ray companion was large enough for it to be a black hole. In addition, an animation combines a wide field image of Cygnus X-1 in visible light with an x-ray image of it; and an illustration depicts material from a massive companion star being pulled into a disk around Cygnus X-1. This resource is part of the NOVA: Black Hole Apocalypse Collection.
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