Years after ripping stars to shreds, 24 black holes suddenly flared up with radio waves in inexplicable 'burping' bouts. Half of all star-killing black holes may experience the same.

Black holes keep ‘burping up’ stars they destroyed years earlier, and astronomers don’t know why::Years after ripping stars to shreds, 24 black holes suddenly flared up with radio waves in inexplicable ‘burping’ bouts. Half of all star-killing black holes may experience the same.