Sentence:  The standard X-ray binary Cyg Xl, with a massive BH candidate, is a <WSD>runaway</WSD>, This could suggest that a SN explosion occurred. Cluster ejection to make a <WSD>runaway</WSD> can not be excluded although in the case of Cyg Xl, the progenitor <WSD>runaway</WSD> must have been a binary 
Meaning of the word marked with <WSD> tags:  An object or process that is out of control or out of equilibrium.