Veil Nebula

Southeastern portion of the constellation of Cygnus. One of the most intense phenomena that can occur in the universe is a supernova explosion. It can happen in two ways: the first when a massive star runs out of “fuel” and begins to collapse under its own gravity; the second when a “white dwarf” accretes material from a companion star and reaches critical mass. In both cases the collapse ends in an immense explosion that completely disintegrates the original object, by then made of degenerate matter: the star's outer layers are ejected at thousands of kilometres per second, creating a cloud of gas and dust in the interstellar medium. This is how a “diffuse supernova remnant” is born. The Veil Nebula is therefore what remains of a supernova that exploded thousands of years ago: three groups of waves of diffuse material, by now enormous and destined to disperse into the interstellar medium, three “veils” of gas and dust that trace a ring roughly 50 light-years across in the sky. The main objects visible today are NGC 6960, NGC 6974 and NGC 6979, with their concave sides facing east, and NGC 6992 and NGC 6995, with their concave sides facing west.