A planetary nebula is a shell of ionized gas and plasma that is expelled by a dying star in the late stages of its evolution, specifically after it has shed its outer layers. Despite the name, planetary nebulae have no relation to planets; the term originates from their round, disk-like appearance when viewed through a telescope. These nebulae often have a bright central core, which is the exposed hot core of the star, and they emit light in various colors due to the ionization of gases like hydrogen, oxygen, and nitrogen.
- Formed when a medium-sized star (like the Sun) sheds its outer layers at the end of its life, leaving behind a hot core.
- Shells of ionized gas from dying stars.
- The ionized gas shell around the core emits light, often creating a shell-like structure.
- Ring Nebula (M57): Located in the constellation Lyra, it resembles a ring or donut shape.
- Dumbbell Nebula (M27): One of the brightest planetary nebulae visible.
