Discovery of an inner light-echo ring around SN 1987A

摘要: The detection of an inner light echo around SN 1987A based on observations made in January, 1989, is reported. An examination direct CCD images reveals a third, light-echo ring the with mean radius 8.2 arcsec and width 3.0 arcsec, so that scattering material distributed between radii 3.1 5.7 pc from supernova. difference brightness eastern western sides indicates not uniformly attributed to shell red-supergiant wind was decelerated by its interaction surrounding medium. fact discovery only 1989 implies there cavity dust along line sight toward earth; therefore, outside became illuminated at end 1988. 26 refs.