Ring Nebula

The Ring Nebula is a planetary nebula in Lyra, catalogued as Messier 57 and NGC 6720. Its glowing shell of ionized gas surrounds a hot central remnant.

Planetary nebula: An expanding shell of ionized gas expelled by a low- or intermediate-mass star late in its evolution. The Ring Nebula is a nearby, well-studied example of this stellar end stage.
Messier 57: The Messier catalogue designation for the Ring Nebula, a planetary nebula in Lyra. This is the Ring Nebula's best-known catalogue name.
Stellar evolution: The changes in a star's structure and properties over its lifetime, driven by nuclear fuel use and gravity. The Ring Nebula formed during the late evolution of its progenitor star.
Dumbbell Nebula: A bright planetary nebula in Vulpecula, catalogued as Messier 27. Its two-lobed appearance contrasts with the Ring Nebula's roughly annular view.
White dwarf: A compact stellar remnant supported against gravity by electron degeneracy pressure. The hot central remnant supplies radiation that ionizes the Ring Nebula's gas.
NGC 6720: The New General Catalogue designation for the Ring Nebula in Lyra. This catalogue entry identifies the same object under a different astronomical naming system.
Asymptotic giant branch: A late phase of stellar evolution in which a star develops a cool, luminous envelope around an inert core. Its progenitor expelled much of its envelope during this late stellar phase.
Helix Nebula: A large, nearby planetary nebula in Aquarius, catalogued as NGC 7293. It offers another detailed view of gas expelled by a dying star.
Photoionization: The removal of electrons from atoms or molecules by absorbed photons. Ultraviolet light from the central star produces the nebula's glowing ionized gas.
James Webb Space Telescope: A space observatory that conducts infrared astronomy using a segmented mirror and instruments operating beyond visible wavelengths. Its infrared observations reveal dusty structures and molecular features within the Ring Nebula.

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