Dwarf stars
An artist's impression of a planet with two exoplanets orbiting in the habitable zone of a red dwarf. Image source: [1]
Although its name leads to think of stars smaller than usual, in fact, dwarf stars constitute the largest group of stars and represent normal in stellar astrophysics. Stars are called dwarfs that are in the main phase of their life, from the time they are born until hydrogen is exhausted at its core, as opposed to the so-called giant stars, which are larger in size. This phase, known as main sequence, constitutes practically ninety percent of the life of the star. So the vast majority of stars are dwarfs.
Our Sun, for example, with its 697,000 km radius, is considered a dwarf star. Antares, a star of the constellation Scorpion, which has a diameter equivalent to 285 times that of the Sun (it is so large that placed in its place would occupy space until the orbit of Mars), is a supergiant.
White dwarf: A white dwarf is a stellar remnant that is generated when a star of mass less than 9-10 solar masses has exhausted its nuclear fuel. In fact, it is a stage of stellar evolution that will penetrate 97% of the stars we know, including the Sun. White dwarfs are, along with red dwarfs, the most abundant stars in the universe.
Blue dwarf: The color of a star is an indicator of its mass and temperature, with blues being warmer than red. The more mass a star has, the faster it consumes its hydrogen, so it is expected that a blue giant will take less time than a red dwarf to abandon the main sequence.
Red dwarf: Red dwarfs are very low-mass stars, less than 40% of the mass of the Sun. Their interior temperature is relatively low and energy is generated at a slow rate by nuclear fusion of hydrogen in helium through Proton-proton chain. Consequently, these stars emit little light, with a luminosity that in some cases hardly reaches 1 / 10,000 of the solar luminosity. Even the largest red dwarf has only 10% of the sun's brightness.
Yellow dwarf: they are mid-sized dwarf stars. A yellow dwarf is a star that belongs to the main sequence of spectral type G and a weight of between 0.7 and 1 times the solar mass. About 10% of the stars in the Milky Way are yellow dwarfs. They have a surface temperature of about 6000 °C.
More details here: Dwarf stars
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