Astronomers Peg Brightness of History’s Brightest Star

The image on the left shows the brightest region of the expanding shell around supernova remnant 1006 A.D. as it appeared in 1998. The long filamentary structure extending across the image is glowing hydrogen gas that has recently been excited by the shock wave from the supernova. In the image at right, this image has been subtracted from an earlier one to show the outward motion of the shock wave over 11 years. The white trace shows its position in 1987, and the dark trace shows it in 1998. The images were obtained from the Cerro Tololo Inter-American Observatory and the Las Campanas Observatory, both in Chile. An animation of the expansion shell is also available below.