In 1987, astronomers spotted a supernova in a neighboring galaxy, so close that the blast could be studied for decades. Now, the ALMA radio telescope, perched high in the Chilean Andes, has allowed us to look inside the remnant and create a three-dimensional map of its molecules. It's like slicing into a layered cake to see how the filling settled between the layers.
Carbon monoxide (CO) and silicon monoxide (SiO) molecules glow in radio wavelengths, and their emission reveals where and how much material was ejected in the explosion. The team compared these maps with simulations of ten different stellar death scenarios. The best matches were models where the star before the explosion was a blue supergiant formed from the merger of two stars. Such a merger stirs up the stellar material, making the explosion asymmetric.
The CO map also points to where the neutron star, the superdense remnant of the core, was sent flying. Based on the material distribution, it is moving almost toward us, at an angle of about 45 degrees north of the remnant's center. If so, we are viewing the explosion almost along the 'trajectory' of the ejected core.
Supernova 1987A has become the most studied in history: its light reached Earth when the explosion occurred in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. Now, for the first time, we can see its interior in 3D, and test how massive stars actually die.
Light from supernova 1987A took 168,000 years to reach Earth, the explosion happened when Neanderthals still roamed our planet.
In Arthur C. Clarke's novel '2010: Odyssey Two', a supernova in a neighboring galaxy becomes a pivotal event for humanity — much like the real SN 1987A, but with less drama.