nuclear fusion
gravitational equilibrium
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positron
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nuetrino
A neutrino (Italian pronunciation: [neuˈtriːno], meaning "small neutral one"; English pronunciation: /njuːˈtriːnoʊ/) is an elementary particle that usually travels close to the speed of light, is electrically neutral, and is able to pass through ordinary matter almost undisturbed.
brown dwarf
are sub-stellar objects which are too low in mass to sustain stable hydrogen fusion. Their mass is below that necessary to maintain hydrogen-burning nuclear fusion reactions in their cores, as do stars on the main sequence, but they have fully convective surfaces and interiors, with no chemical differentiation by depth. Brown dwarfs occupy the mass range between that of large gas giant planets and the lowest-mass stars;
nuclear fusion
the process in which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy. Large scale thermonuclear fusion processes, involving many nuclei fusing at once, must occur in matter at very high densities and temperatures.