Supernova explosions of the star is the only source of heavier elements in the Universe. All the heavier elements (like iron, are more heavy ones) are being created during these explosions and are spread around the space to create later planetary systems. One of these remarkable explosions happened about 10 000 years ago in the constellation of Cygnus. It created Veil Nebula placed about 1440 light years away which is now 80 light years large and still expands at speed 170km/s. Small part of this nebula is Pickering’s Triangle presented below.
It was pictured by me about half year ago, but a few days ago I found these files during the disk clean up. Red regions corresponds to the hydrogen, and blue ones to oxygen. It is bicolor composition of two monochrome frames shot with the proper narrowband filters.