Fig11_9 A light echo

Fig11_9 A light echo

Fig. 11.9 . Two complete rings of light surround the exploded star SN 1987A in this negative image taken with the 3.9-m (153.5-inch) Anglo-Australian Telescope on 15 July 1988. The initial flash of light from the supernova explosion has been reflected off clouds of interstellar dust, and observed 14 months after the explosion was brightest, somewhat like an echo of sound. These light echoes arise in two thin sheets of microscopic dust grains located about 470 light-years (inner ring) and 1,300 light-years (outer ring) in front of the supernova. The rings have been made more prominent by photographically subtracting an image taken three years before the supernova exploded, canceling much that existed previously. Stars, however, are still visible as faint haloes. (Courtesy of David Malin and the Anglo-Australian Observatory.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University