The most commonly used definition is: A star, such as the sun, having relatively low mass, small size, and average or below average luminosity (brightness).
The second definition is: A star of relatively small size and low luminosity, including the majority of main sequence stars
The first dwarf star was discovered by Friedrich Wilhelm Herschel on January 31, 1783. Dwarf Stars are burned out stars that used up all of their hydrogen and then became red giants before a great collapse into very dense matter.If a dwarf star forms in a multiple star system, it may become a nova. Nova stars were once believed to be new stars. Today, we understand that they are very old stars, white dwarfs. Its been predicted that in 5 billion years hydrogen in the Sun will fuse, pulling more matter to the core. A shell will cover the sun and cool it turning the sun redder. It will greatly expand and possibly destroy Mercury, Venus, and Earth. In the end it will become a white dwarf star. White dwarfs can be the size of Earth, but still have the mass of a star. Fast moving electrons provide pressure to keep the star from collapsing. A dwarf stars mass is about 20 sols, and it has a luminosity of about 20,000 sols (sols can mean the mass of the sun or the luminosity of the sun).
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