dwarf star

noun

, Astronomy.

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

dwarf star

noun

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

dwarf star

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.

Word History and Origins

Origin of dwarf star¹

First recorded in 1910–15

A 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.

Example Sentences

Image: A ring of glowing remains of the first-ever recorded supernova, a white dwarf star that exploded more than 1800 years ago.

From Space Scoop

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

From Science Daily

This is made up of seven planets, all roughly in Earth's size range and likely rocky, orbiting a red dwarf star.

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

It's against this backdrop that the SPECULOOSconsortium, led by the University of Liège, has just announced the discovery of a new Earth-sized planet orbiting a nearby ultra-cool dwarf star.

From Science Daily