The unusual K-band characteristics of the gravitational lens system MG 1131 + 0456

The radio morphology of the gravitational lens system MG 1131+0456 is that of an "Einstein ring." Newly obtained K'-band images of the system reveal the presence of an infrared bright object that has a morphology reminiscent of that seen in the radio. There are two bright objects embedded in an elliptical halo; these seem to be the infrared counterparts to the radio morphology. Two nearby objects have no radio counterparts. All four objects have extremely red optical-infrared colors: R - K > 6. Few extragalactic objects are this red. A plausible candidate for the source object is an unusually red radio galaxy.