The Honeycomb supernova remnant

At 2′.5 southeast of SN 1987 A, the Honeycomb Nebula is named after its interesting morphology, which consists of over ten loops with sizes of 2-3 pc. High-dispersion spectra of these loops show hemispheres expanding toward the observer at 100-300 km s^-1. Using archival X-ray data and a combination of new and archival radio data, we find bright X-ray and nonthermal radio emission associated with the Honeycomb Nebula. New CCD images further show enhanced [S II]/Hα ratios. These results confirm a model in which the Honeycomb Nebula is due to a supernova shock front, traveling toward the observer, encountering an intervening sheet of dense, but porous, interstellar gas. The bulk of the supernova remnant resides in a low-density cavity, and is not otherwise visible. The situation is similar to the hidden supernova remnants postulated for the X-ray bright superbubbles. The Honeycomb Nebula has an unusually steep radio spectral index (S_v ∝ v^-1.2), normally associated with young SNRs.