The "Smoking Gun" of the Nearest Known Supernova

Illinois researchers Peter McCullough, Brian Fields, and Vasiliki Pavlidou have discovered evidence for a very nearby supernova explosion in the relatively recent past. A survey of H-alpha emission due to ionized gas (black in the image) reveals a feature in the left center of the image, located above the plane of our galaxy (the dark regions below). This feature shows filaments and shell structure characteristic of the aftermath of the explosion--a "supernova remnant." The remnant spans 20 degrees across, looming so large that is has been overlooked in more narrowly focused sky surveys.

The large angular size of the remnant also implies that it is very close to us, and thus presents us with a unique supernova laboratory. For example, this remnant is the first seen in high-energy gamma-rays (white contours), which are the signatures of radioactive aluminum created in supernovae. Also, the closeness of the remnant raises hope of finding a neutron star created in the explosion. The yellow +'s mark the path of a nearby pulsar, which is now located in the upper right, but is moving away from the supernova remnant, and about 2 million years ago "hit the bullseye" of the remant and its radioactive ejecta, suggesting a common origin.

The picture emerges of a supernova explosion about 2 million years ago. at a distance of about 300 light years. This is the closest known supernova remnant, which our ancestors would have seen shining nearly as bright as the full moon.

More information appears in the published paper and in a brief article in New Scientist