Planetary Nebulae

"Planetary nebulae (PNe) occupy a pivotal position in several branches of modern astrophysics. They are the chief source in the Universe of carbon, the basic constituent of life, and of s-process elements, which in the solar system, dominate the abundances of elements heavier than the iron-group. In terms of stellar evolution, PNe provide a link between the last ascent of the red giant branch (the asymptotic giant branch, or AGB) and the white dwarf end-point to the life of low- and intermediate-mass stars. PNe enrich the surrounding interstellar medium and directly influence the next generation of star formation, thus having important implications for galactic evolution." -- UCL Department of Physics & Astronomy - Astrophysics Group

Soap Bubble Nebula (PN G75.5+1.7)

Credit: T. A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN and NOAO/AURA/NSF