Brown Dwarf

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Introduction1

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Encyclopedia

Brown dwarfs are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen (1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most massive gas giant planets and the least massive stars, approximately 13 to 80 times that of Jupiter (MJ). However, they can fuse deuterium (2H), and the most massive ones (> 65 MJ) can fuse lithium (7Li). Astronomers classify self-luminous objects by spectral class, a distinction intimately tied to the surface temperature, and brown dwarfs occupy types M, L, T, and Y. As brown dwarfs do not undergo stable hydrogen fusion, they cool down over time, progressively passing through later spectral types as they age. Despite their name, to the naked eye, brown dwarfs would appear in different colors depending on their temperature. The warmest ones are possibly orange or red, while cooler brown dwarfs would likely appear magenta to the human eye. Brown dwarfs may be fully convective, with no layers or chemical differentiation by depth. — Wikipedia

Brown Dwarf (Encyclopædia Britannica)

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Innovation

Science

What is a Brown Dwarf? (JPL/NASA)

Brown Dwarf (Wolfram Alpha)

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Preservation

History

The objects now called “brown dwarfs” were theorized by Shiv S. Kumar in the 1960s to exist and were originally called black dwarfs, a classification for dark substellar objects floating freely in space that were not massive enough to sustain hydrogen fusion. However, (a) the term black dwarf was already in use to refer to a cold white dwarf; (b) red dwarfs fuse hydrogen; and (c) these objects may be luminous at visible wavelengths early in their lives. Because of this, alternative names for these objects were proposed, including planetar and substar. In 1975, Jill Tarter suggested the term “brown dwarf”, using “brown” as an approximate color. — Wikipedia

Library

Melvil Decimal System # 523.88 Dwarf Stars (Library Thing)
Library of Congress Subject Heading: Brown Dwarf (Library Thing)

Library of Congress # QB843.D9 Dwarf stars (UPenn Online Books)

WorldCat, Library of Congress, UPenn Online Books, Open Library

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Participation

Education

MERLOT: Multimedia Educational Resource for Learning and Online Teaching
OER Commons: Open Educational Resources

Community

News

Brown Dwarf (Astronomy Magazine)
Brown Dwarf (Phys.org)
Brown Dwarf (NPR Archives)

Government

Document

Brown Dwarf (USA.gov)

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Related

Here are links to pages about closely related subjects.

Knowledge Realm

Physical

“Fundamentals”
Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle

“Space”
Universe (Astronomical Instrument)
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Our Neighborhood
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid

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Notes

1.   The resources on this page are are organized by a classification scheme developed exclusively for Cosma.