dwarf star

American  

noun

Astronomy.

1. any of the ordinary main sequence stars, as those of spectral types O, B, A, F, G, K, and M.

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dwarf star British  

noun

1. Also called: main-sequence star.  any luminosity class V star, such as the sun, lying in the main sequence of the Hertzsprung-Russell diagram See also red dwarf white dwarf

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dwarf star Scientific  

1. A relatively small, low-mass star that emits an average or below-average amount of light. Most dwarf stars, including the Sun, are main-sequence stars, the principal exception being white dwarfs, which are the remnants of larger collapsed stars. Main-sequence dwarfs burn their hydrogen at a much slower rate than giant and supergiant stars and are consequently less luminous and have longer lifespans than those non-main-sequence stars do.

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Closer Look

Despite their diminutive name, most dwarf stars are quite normal main-sequence stars and come in a wide variety of sizes, formed from protostars with sufficient mass to begin the process of nuclear fusion. But there are other stellar and quasistellar objects called dwarf stars as well. Brown dwarfs are formed when insufficient mass accretes for nuclear fusion to take place; brown dwarfs thus never become proper stars. Other kinds of dwarf stars result from the further evolution of main-sequence stars not massive enough to become neutron stars or black holes (which form from the burned-out core of a supernova). The type known as a white dwarf is the remnant of a red giant star that has burned nearly all its fuel. The mutual gravitational attraction of its atoms, no longer counterbalanced by the outward pressure of burning fuel within, causes the star to collapse in on itself. After it contracts and blows its outer layers away as a planetary nebula, the red giant stabilizes as a white dwarf and slowly fades. Our Sun is of a size and mass that will probably cause it to evolve first into a small red giant and eventually into a white dwarf. Red dwarfs have a lower mass and luminosity than white dwarfs, and black dwarfs, if any yet exist, are even less luminous, no longer giving off any detectable radiation.

Etymology

Origin of dwarf star

First recorded in 1910–15

Example Sentences

Of the seven Earth-sized planets circling the red dwarf star TRAPPIST-1, one world has become a special focus for astronomers.

From Science Daily

However, TRAPPIST-1 is a so-called M dwarf star, only about one tenth the size of the sun and just slightly larger than Jupiter.

From Science Daily

"While the sun is a bright, yellow dwarf star, TRAPPIST-1 is an ultracool red dwarf, meaning it is significantly smaller, cooler and dimmer than our sun," he explained.

From Science Daily

One is so close to its orange dwarf star it completes orbit in less than 12 hours.

From Science Daily

It orbits a cool red dwarf star called Gliese 12, which is almost 40 light-years away from Earth in the constellation Pisces.

From Science Daily