Antimatter Hypothesis: "Rotten Egg" Nebula

NASA, ESA, William B. Latter (SIRTF Science Center/California Institute of Technology), John H. Bieging (University of Arizona), Casey Meakin (University of Arizona), A.G.G.M. Tielens (Kapteyn Astronomical Institute), Aditya Dayal (IPAC/NASA Jet Propulsion Laboratory), Joseph L. Hora (Center for Astrophysics), and Douglas M. Kelly (University of Arizona)
Sulfur was detected in the gas from this planetary nebula giving it the “Rotten Egg” nickname. The gas contains molecules of hydrogen sulfide and sulfur dioxide, which are detected in their spectra. Sulfur is one row beyond oxygen in the periodic table. The black and white image is ultraviolet, and its matching color image is a composite of four ultraviolet filtered images. A color filter only records light in a narrow range. These images then assign a color to each black and white image and make a composite image. Ultraviolet is not visible to the human eye.

NASA/ESA & Valentin Bujarrabal (Observatorio Astronomico Nacional, Spain)
In the yellow and blue image of the same celestial object the ejecta appears in yellow and collisions with the surrounding material appear in blue.