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A type of emission nebula characterized by ionized hydrogen, often found in the arms of spiral galaxies and associated with regions of current or recent star formation.

A small, dense, and dark cloud of dust and gas within a H II region or molecular cloud, often seen as isolated and rounded objects, and thought to be precursors to star formation.

A shell of ionized gas ejected from red giant stars late in their lives. The name arises from the round, planet-like appearance in small telescopes.

A cloud of ionized gas emitting light of various colors, formed by ionized hydrogen. Stars forming within these nebulae make the gas glow.

A dense cloud of gas and dust that blocks the light from stars and other astronomical objects behind it, making it appear as a dark silhouette against the brighter background.

A nebula formed from the material ejected from a Wolf-Rayet star, which is a massive star in a late stage of stellar evolution with a high mass loss rate through powerful stellar winds.

A small patch of nebulosity associated with newborn stars, formed when fast-moving narrow jets of partially ionized gas ejected by the star collide with nearby clouds of gas and dust.

A cold, dense cloud of molecular hydrogen and other molecular gases, which are the principal regions of star formation in galaxies.

A nebula surrounding a star, representing material ejected from the star or left over from its formation, often seen in different stages of a star's life cycle.

A type of nebula that represents a short stage in stellar evolution, occurring as a result of a star shedding its outer layers and before it becomes a planetary nebula.

Nebulae that shines by reflecting the light of nearby stars, typically blue in color due to shorter wavelengths scattering more efficiently.