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The Yerkes spectral classification, also called the MK, or Morgan-Keenan (alternatively referred to as the MKK, or Morgan-Keenan-Kellman) [18] [19] system from the authors' initials, is a system of stellar spectral classification introduced in 1943 by William Wilson Morgan, Philip C. Keenan, and Edith Kellman from Yerkes Observatory. [20]
Below there are lists the nearest stars separated by spectral type. The scope of the list is still restricted to the main sequence spectral types: M, K, F, G, A, B and O. It may be later expanded to other types, such as S, D or C. The Alpha Centauri star system is the closest star system to the Sun.
The classes of the stars and brown dwarfs are shown in the color of their spectral types (these colors are derived from conventional names for the spectral types and do not necessarily represent the star's observed color).
The Henry Draper Catalogue (HD) is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension (HDE), published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the Henry Draper Extension Charts (HDEC), published from 1937 to 1949 in the form of charts ...
The spectral type is not a numerical quantity, but the sequence of spectral types is a monotonic series that reflects the stellar surface temperature. Modern observational versions of the chart replace spectral type by a color index (in diagrams made in the middle of the 20th Century, most often the B-V color) of the stars.
This is a list of O-type stars by their distance from Earth. [1] [2] [3] List. Milky Way galaxy. ... Stars in system Spectral type Apparent magnitude (V)
The current star in the North Pole. It is a Classical Cepheid variable, and the brightest example of its class. Aldebaran (α Tauri) 45.1 ± 0.1 [94] AD Fourteenth brightest star in the night sky. Arcturus (α Boötis) 25.4 ± 0.2 [95] AD This is the nearest red giant to the Earth, and the fourth brightest star in the night sky. Pollux (β ...
Comparison of main sequence stars of each spectral class. By treating the star as an idealized energy radiator known as a black body, the luminosity L and radius R can be related to the effective temperature T eff by the Stefan–Boltzmann law: = where σ is the Stefan–Boltzmann constant. As the position of a star on the HR diagram shows its ...