Double Supernova Remnants DEM L316 . ... Credit Copyright: Gemini Observatory , GMOS-South , NSF Explanation: Are these two supernova shells related? ... In particular, the smaller shell appears to be the result of Type Ia supernova where a white dwarf exploded, while the larger shell appears to be the result of a Type II supernova where a massive normal star exploded. ... NASA Web Site Statements, Warnings, and Disclaimers . NASA Official: Jay Norris. ... A service of: LHEA at NASA / GSFC . ...