spectral type

American  

noun

Astronomy.

1. a category for classifying a star, as A star or G star, according to features of its spectrum, as its shape as a function of temperature and wavelength and its absorption spectrum, that indicate the surface temperature of the star and the presence of particular atoms or molecules in its outer layers: principal types are spectral types O, B, A, F, G, K, and M.

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spectral type British  

noun

1. any of various groups into which stars are classified according to characteristic spectral lines and bands. The most important classification ( Harvard classification ) has a series of classes O, B, A, F, G, K, M, the series also being a scale of diminishing surface temperature

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spectral type Scientific  

1. A classification system for stars based on the strength of their spectral lines, using the letters O, B, A, F, G, K, M, L, and T to denote a range from blue (as in blue giant stars) to dim red (as in brown dwarfs). The spectrum of a star correlates with its surface temperature, ranging from over 60,000°K (O type) to less than 3,500°K (L and T types).

2. See also Hertzsprung-Russell diagram

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Etymology

Origin of spectral type

First recorded in 1920–25

Example Sentences

Look up the spectral type of Antares in Appendix J. Was your estimate of the temperature about right?

From Textbooks • Oct. 13, 2016

Since brown dwarfs cool steadily throughout their lifetimes, the spectral type of a given brown dwarf changes with time over a billion years or more from late M through L, T, and Y spectral types.

From Textbooks • Oct. 13, 2016

Measure the spectrum and get the spectral type.

From Textbooks • Oct. 13, 2016

To seek the Milky Way’s farthest-flung residents Bochanski's team started with nearly seven million stars, using near-infrared data to select those whose colors match spectral type M, which designates stars that are cool and red.

From Scientific American • Aug. 11, 2014

A third drift, to which all the Orion stars belong, is under investigation, together with comprehensive analysis of the drifts according to the spectral type of all the stars included.

From Astronomy: The Science of the Heavenly Bodies by Todd, David Peck