Sky science
Brown Dwarf
Direct answer
Brown Dwarf: A Brown Dwarf is a substellar object too low in mass to sustain ordinary hydrogen fusion like a star.
It occupies the regime between giant planets and stars.
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At a glance
- Found in
- Astronomy & Skywatching
- Related
- Red Supergiant, White Dwarf, Neutron Star, Pulsar
It occupies the regime between giant planets and stars.
A scientific orientation to scale, light, or motion; the article supplies the precise definition.
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The story behind Brown Dwarf
Infrared surveys discovered large populations of cool brown dwarfs late in the twentieth century.
A one-minute story
The Wandering Stars
How the moving planets were watched, named and found, and what a transit is.
Why Brown Dwarf matters
Brown Dwarf tests formation, atmospheres, clouds, and the lower-mass boundary of stellar physics.
How to read Brown Dwarf
Classify with mass, spectrum, age, and formation context rather than one temperature.
Brown Dwarf in practice: an example
Some brown dwarfs briefly fuse deuterium yet never join the hydrogen-burning main sequence.
Where readings of Brown Dwarf go wrong
The boundary with giant planets is not defined by appearance alone.
Sources and editorial method
Research references used for this entry include:
- NASA Science: Stars - NASA overview of stellar birth, main-sequence evolution, giant phases, remnants, and supernovae.
- NASA Science: Universe Glossary - NASA definitions for common stellar, galactic, orbital, and high-energy astronomy terms.
- Source
- The Great Almanac Dictionary
- Category
- Astronomy & Skywatching
- Last updated
- 2026-09-26
Meet a substellar world
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More in Astronomy & Skywatching
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- Reference Epoch
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- True Anomaly
- Apparent Magnitude
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Common questions
What is a Brown Dwarf?
A Brown Dwarf is a substellar object too low in mass to sustain ordinary hydrogen fusion like a star.
What do people get wrong about a Brown Dwarf?
The boundary with giant planets is not defined by appearance alone.
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