Deep-sky object class · e.g. The Orion Nebula (M42)

HII Region

A large cloud of ionised atomic hydrogen (H II) surrounding one or more hot O- and B-type stars, whose ultraviolet light strips the electrons from the surrounding gas. HII regions are the glowing signposts of massive-star formation, and their sizes and spectra are used to trace star formation across galaxies.

Highlights

›Ionised hydrogen around newborn massive stars

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Associated withEmission Nebula
Associated withOrion Nebula
Associated withEmission Nebula
Associated withSharpless Catalogue
Associated withStar-Forming Regions
Associated withThe Cone Nebula
Associated withNarrowband Imaging

Sources

Facts on this topic will be cited from these primary and reference sources.

NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.

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HII Region

Highlights

Examples & related concepts

Across the encyclopedia

Knowledge connections

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HII Region

Highlights

Examples & related concepts

Across the encyclopedia

Knowledge connections

Sources