This artist’s impression shows a binary system containing a stellar-mass black hole known as IGR J17091 for short. Observations with Chandra have clocked the fastest wind ever seen blowing off a disk around this stellar-mass black hole at about 20 million miles per hour. The wind, which comes from a disk of gas surrounding the black hole, may be carrying away much more material than the black hole is capturing and could be variable over time. This result has important implications for understanding how this class of black hole, which typically weighs between 5 and 10 solar masses, can behave.