Complex sentence: He is perhaps best known for his discovery, with Guillermo Haro, of the Herbig-Haro objects; bright patches of nebulosity excited by bipolar outflow from a star being born.
Split into simpler sentences: He is perhaps best known for the discovery of Herbig-Haro objects. He was perhaps best known for his discovery, with Guillermo Haro, of the Herbig-Haro objects; bright patches of nebulosity excited by bipolar outflow from a star being born.