The Red Rectangle Nebula
"The Red Rectangle is an unusual example of what is known as a proto-planetary nebula. These are old Sun like stars, on their way to becoming planetary nebulae. Once the expulsion of mass is complete a very hot white dwarf star will remain and its brilliant ultraviolet radiation will cause the surrounding gas to glow. The Red Rectangle is found about 2 300 light-years away in the constellation Monoceros (the Unicorn)."
ESA/Hubble and NASA