Search results
Results from the WOW.Com Content Network
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 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.
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 ...
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).
A giant star has a substantially larger radius and luminosity than a main-sequence (or dwarf) star of the same surface temperature. [1] They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsprung–Russell diagram and correspond to luminosity classes II and III. [2]
Antares is a red supergiant star with a stellar classification of M1.5Iab-Ib, and is indicated to be a spectral standard for that class. [6] Due to the nature of the star, the derived parallax measurements have large errors, so that the true distance of Antares is approximately 550 light-years (170 parsecs) from the Sun. [3]
The primary has a stellar classification of F5IV–V, indicating that it is a late-stage F-type main-sequence star. Procyon A is bright for its spectral class, suggesting that it is evolving into a subgiant that has nearly fused its hydrogen core into helium, after which it will expand as the nuclear reactions move outside the core. [3]