Nucleosynthesis

 

 

Discovery of an Old, Nearby, and Overlooked Supernova Remnant

Multi-wavelength evidence, summarized in the image to the left, suggest that a very nearby supernova explosion occured in the relatively recent past in the southern constellation of Antlia Pneumatica. The proximity of the resulting supernova remnant makes it an ideal site for the observational study of supernova nucleosynthesis.

H-alpha emission (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 a supernova remnant. The remnant spans 20 degrees across, looming so large that is has been overlooked in more narrowly focused sky surveys.

This remnant is the first seen in high-energy gamma-rays (white contours), which are the signatures of radioactive aluminum created in supernovae. 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 "best-guess" vital statistics of the object are that it originated in 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.

Reference: McCullough, P.R., Fields, B. D. & Pavlidou, V. 2002, ApJ, 576, L41
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