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A stellar association is a very loose star cluster, looser than an open cluster. A moving group is the remnant of such a stellar association. [1] Members of stellar associations and moving groups share similar kinematic properties, as well as similar ages and chemical composition. The list (below) is sorted by the distance to the Solar System.
The BCG of this cluster was also the most distant galaxy of the time. [51] [53] Gemini Cluster 1932 − 1936 0.075 23 000 The BCG of this cluster was the most distant galaxy at the time. [53] [54] WH Christie's Leo Cluster 1931–1932 19 700 The BCG of this cluster was the most distant galaxy known at the time. [51] [54] [55] [56] [57]
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 term "The Local Group" was introduced by Edwin Hubble in Chapter VI of his 1936 book The Realm of the Nebulae. [11] There, he described it as "a typical small group of nebulae which is isolated in the general field" and delineated, by decreasing luminosity, its members to be M31, Milky Way, M33, Large Magellanic Cloud, Small Magellanic Cloud, M32, NGC 205, NGC 6822, NGC 185, IC 1613 and ...
NGC 6397 (also known as Caldwell 86) is a globular cluster in the constellation Ara that was discovered by French astronomer Nicolas-Louis de Lacaille in 1752. [9] It is located about 7,800 light-years from Earth, [3] making it one of the two nearest globular clusters to Earth (the other one being Messier 4).
Galaxy morphological classification is a system used by astronomers to divide galaxies into groups based on their visual appearance. There are several schemes in use by which galaxies can be classified according to their morphologies, the most famous being the Hubble sequence , devised by Edwin Hubble and later expanded by Gérard de ...
The revised Yerkes Atlas system [7] listed a dense grid of A-type dwarf spectral standard stars, but not all of these have survived to this day as standards. The "anchor points" and "dagger standards" of the MK spectral classification system among the A-type main-sequence dwarf stars, i.e. those standard stars that have remained unchanged over years and can be considered to define the system ...