Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. If alone, a black hole would indeed appear quite black, but many black hole candidates are part of binary star systems . A black hole system so equipped would appear much darker than a similar neutron star system. The difference is caused by the hot gas from the ADAF disk falling through the event horizon of the black hole and disappearing - gas that would have emitted much light were the central object only a neutron star. V404 Cyg has yielded a spectrum much like an ADAF onto a black hole - and perhaps brighter than allowable from an ADAF onto a neutron star.
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