Supernova 1987A was the first supernova (hence the “A”) discovered in the year 1987. The supernova occurred in the Large Magellanic Cloud, a neighbouring galaxy to the Milky Way. A supernovae explosion sends a shock wave into the surrounding circumsteller environment, and may leave a neutron star at the core of the resulting supernova remnant. A rotating neutron star may be detected as a radio pulsar, and a number of observations have been made in the years since searching for a pulsed signal — without success.

Crawford and Xu have reprocessed the available archival radio pulsar search observations of SNR 1987A taken with Murriyang, the Parkes 64-m telescope, some of which have not been previously published. Despite advanced algorithms and greater processing power, no evidence for pulsed signals was found. There may still be a pulsar, just not beamed our way, or alternatively the plasma in the inner supernova remnant may still be optically thick at the ~GHz frequencies used.

In the absence of any pulses, the image above is a James Webb Space Telescope NIRCam (Near-Infrared Camera) image of the SNR 1987A. The center of the supernova remnant is packed with clumpy gas and dust ejected by the supernova explosion. The dust is so dense that even near-infrared light that JWST detects can’t penetrate it, shaping the dark “keyhole” in the centre. A bright, equatorial ring surrounds the inner keyhole, forming a band around the waist that connects two faint arms of hourglass-shaped outer rings. The equatorial ring, formed from material ejected tens of thousands of years before the supernova explosion, contains bright hot spots, which appeared as the supernova’s shock wave hit the ring. The JWST image now reveals spots exterior to the ring, with diffuse emission surrounding it. These are the locations of supernova shocks hitting more exterior material. In this JWST image, blue represents light at 1.5 microns (F150W), cyan 1.64 and 2.0 microns (F164N, F200W), yellow 3.23 microns (F323N), orange 4.05 microns (F405N), and red 4.44 microns (F444W). (Image credit: NASA, ESA, CSA, M. Matsuura (Cardiff University), R. Arendt (NASA’s Goddard Spaceflight Center & University of Maryland, Baltimore County), C. Fransson (Stockholm University), J. Larsson (KTH Royal Institute of Technology), A. Pagan (STScI))