The circumstellar environment of rotating Wolf-Rayet Stars and the   implications for GRB afterglows
  If Wolf-Rayet stars are the progenitors of Gamma-ray bursts (GRBs), they must rotate rapidly to produce the GRB. This rotation may effect their stellar-wind bubbles and possibly explain why so many GRB afterglows occur in a constant density medium. 
J.J. Eldridge