A white dwarf which has stopped radiating energy.

1. A gaseous body smaller in mass than a star, but larger than a planet.
2. An object less massive than a star, but heavier than a planet.

Brown dwarfs do not have enough mass to ignite nuclear reactions at their centers, but shine by heat released during their contraction from a gas cloud.

Some astronomers believe that vast numbers of brown dwarfs exist throughout the galaxy, but because of the difficulty in detecting them, none of them were detected until 1995, when U.S. astronomers discovered a brown dwarf, in the constellation Lepus (Hare).

A celestial body that orbits the sun and has a spherical shape but is not large enough to disturb other objects from its orbit.

A small, relatively cool star with low luminosity.

1. A dense, small low-luminosity star of mass less than the Chandrasekhar limit (1.4 solar masses) left as the remnant of a supernova explosion.
2. A type of star that has collapsed after exhausting its nuclear fuel.

Leftover heat causes it to shine faintly.

A star may remain a giant or supergiant for several million years before all nuclear reactions cease.

Gravitational collapse then occurs with no outward pressure to stop it, and the final result may be a white dwarf.

Such a star is small, about the same size as the earth, but has about one million times the density of water and the temperature at the surface is a hundred thousand degrees, yet the luminosity is quite low; about one-thousandth of the sun.