Cygnus X-1 contains a 21-solar mass black hole-Implications for massive star winds

Miller-Jones, JCA; Bahramian, A; Orosz, JA; Mandel, I; Gou, LJ; Maccarone, TJ; Neijssel, CJ; Zhao, XS; Ziolkowski, J; Reid, MJ; Uttley, P; Zheng, XY; Byun, DY; Dodson, R; Grinberg, V; Jung, T; Kim, JS; Marcote, B; Markoff, S; Rioja, MJ; Rushton, AP; Russell, DM; Sivakoff, GR; Tetarenko, AJ; Tudose, V; Wilms, J