main sequence

American  

noun

Astronomy.

1. a narrow band in the Hertzsprung-Russell diagram in which 90 percent of all observed stars are plotted.

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main sequence British  

noun

1. astronomy

   1. a diagonal band on the Hertzsprung Russell diagram containing about 90% of all known stars; stars evolve onto and then off the band during their lifetime

   2. ( as modifier )

      a main-sequence star

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main sequence Scientific  

/ mān /

1. The continuous, generally diagonal line or band in the Hertzsprung-Russell diagram ranging from the upper left to the lower right and representing stars of average size whose luminosities correspond predictably to their surface temperatures. Stars in this grouping maintain a stable nuclear reaction and experience only small fluctuations in luminosity and temperature. Main-sequence stars are believed to be in the stable, middle phase of their development; they are expected to move off the main sequence once the hydrogen in their core is exhausted. At that point, depending on its size, a main-sequence star will become a giant star, a supergiant star, or a white dwarf. The more massive the star, the faster it burns its nuclear fuel and the shorter it remains in the main sequence.

2. See more at Hertzsprung-Russell diagram star

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Etymology

Origin of main sequence

First recorded in 1925–30

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Example Sentences

See Examples For:

main sequence

Younger post-main sequence stars had a higher rate of 0.35%, similar to stars still on the main sequence.

From Science Daily ● Apr. 4, 2026

Located about 11,000 light years from Earth near the constellation Pupis, Gaia20ehk is a stable "main sequence" star similar to our sun.

From Science Daily ● Mar. 11, 2026

EX Hydrae exists in a binary system alongside a normal main sequence star.

From Science Daily ● Jan. 8, 2026

This then is a good explanation of why 90% of all stars are found on the main sequence in the H–R diagram.

From Textbooks ● Oct. 13, 2016

Deep inside my chest, a main sequence star collapsed under its own gravity.

From "Darius the Great Is Not Okay" by Adib Khorram

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