CIRCINUS X-1 - A RUNAWAY BINARY WITH CURVED RADIO JETS

We present high-resolution radio studies at 1.47 and 4.79 GHz, made with the Australia Telescope, which show clear evidence for jet-like structure within the nebula surrounding Cir X-1. The jets originate in a compact source at the position of the binary, then extend outwards about 30 arcsec before curving back several arcmin towards the nearby supernova remnant G 321.9-0.3. This behaviour can be explained if Cir X-1 is a runaway binary from the supernova explosion which gave rise to G 321.9-0.3. When critical accretion occurs, the binary ejects mass in two collimated jets which interact with the surrounding interstellar material, and accelerate relativistic electrons which emit radio continuum by the synchrotron process. The radiating electrons are left behind and form a curved wake extending back towards the SNR.