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dwarf star:see white dwarfwhite dwarf,
in astronomy, a type of star that is abnormally faint for its white-hot temperature (see mass-luminosity relation). Typically, a white dwarf star has the mass of the sun and the radius of the earth but does not emit enough light or other radiation to be easily
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dwarf star(dwarf) Any star lying on the main sequence of the Hertzsprung–Russell diagram. The term arises from the early dual classification of stars into giants (g) and dwarfs (d ): the Sun was classified as d G2. This system has been superseded by that of luminosity classes (see spectral types), and these ‘dwarf’ stars are of luminosity class V. The term main-sequence star is now more common, especially to prevent confusion with white dwarfs; late-type main-sequence stars, however, are still referred to as red dwarfs.
a star of relatively small size and low luminosity. Most dwarf stars form the lower part of the main sequence of the Hertzsprung-Russell diagram. Their average density ranges from 1 to 60 g/cm3. Evidently, all stars of average and small mass are dwarf stars at a certain stage in their evolution, which is characterized by the start of nuclear reactions and the burning of hydrogen in the star’s nucleus. In addition, dwarfs include stars existing in a state of gravitational contraction for a long time because of their very small mass. Dwarf stars have well-developed convection zones and extended chromospheres; therefore, emission lines are encountered in their spectra. A typical dwarf star is our sun. Among dwarfs there are a considerable number of stars with variable characteristics. A large part of the spherical subsystem of the Milky Way Galaxy and of the planar subsystem excluding the spiral arms consists of dwarf stars. The white dwarfs considerably differ in their structure from ordinary (or red) dwarfs.
V. S. AVEDISOVA