National Geographics has a neat feature of the twenty-five greatest photos of the universe, taken by Hubble Space Telescope in its 17 years in service. This one is the Red Rectangle, a protoplanetary nebula in the constellation of Monoceros:
Hubble’s image of HD 44179, a bipolar protoplanetary nebula, called the Red Rectangle, revealed ladderlike structures around a dying star. The ladder rungs may be a product of mass ejections from the nebula.
Gas and dust that HD 44179 emits generate the X shape. Astronomers suspect that hydrocarbons are responsible for the red hue.
A planetary nebula, such as HD 44179, is formed when a red giant transitions to a white dwarf at the end of the star’s life. Gas is expelled from the dying star. The gas makes up the nebula.