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A black dwarf is a theoretical stellar remnant, specifically a white dwarf that has cooled sufficiently to no longer emit significant heat or light. Because the time required for a white dwarf to reach this state is calculated to be longer than the current age of the universe (13.8 billion years), no black dwarfs are expected to exist in the ...
Black dwarf: The final state for a star, like the Sun, that is too small to become either a black hole or a neutron star. It would take a star like the Sun roughly a quadrillion years to reach this state, so none are believed to exist today. — The universe is not old enough for this form to come into existence. Black star
A star in this hypothetical state is called a "quark star" or more specifically a "strange star". The pulsar 3C58 has been suggested as a possible quark star. Most neutron stars are thought to hold a core of quark matter but this has proven difficult to determine observationally. [citation needed]
A substellar object may be a companion of a star, [9] such as an exoplanet or brown dwarf that is orbiting a star. [10] Objects as low as 8–23 Jupiter masses have been called substellar companions. [11] Objects orbiting a star are often called planets below 13 Jupiter masses and brown dwarves above that. [12]
The Hertzsprung–Russell diagram showing the location of main sequence dwarf stars and white dwarfs. A dwarf star is a star of relatively small size and low luminosity. Most main sequence stars are dwarf stars. The meaning of the word "dwarf" was later extended to some star-sized objects that are not stars, and compact stellar remnants that ...
The closest encounter to the Sun so far predicted is the low-mass orange dwarf star Gliese 710 / HIP 89825 with roughly 60% the mass of the Sun. [4] It is currently predicted to pass 0.1696 ± 0.0065 ly (10 635 ± 500 au) from the Sun in 1.290 ± 0.04 million years from the present, close enough to significantly disturb the Solar System's Oort ...
This solid state contrasts with degenerate matter that forms the body of a white dwarf, where most of the electrons would be treated as occupying free particle momentum states. Exotic examples of degenerate matter include neutron degenerate matter, strange matter , metallic hydrogen and white dwarf matter.
Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main-sequence stars.Their mass is approximately 13 to 80 times that of Jupiter (M J) [2] [3] —not big enough to sustain nuclear fusion of ordinary hydrogen (1 H) into helium in their cores, but massive enough to emit some light and heat from the fusion of deuterium (2 H).