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The regions with higher density of stars are shown; these correspond with known star clusters (Hyades and Coma Berenices) and moving groups. This is a list of nearby stellar associations and moving groups. 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 ...
c. 300 BC — star catalog of Timocharis of Alexandria; c. 134 BC — Hipparchus makes a detailed star map; c. 150 — Ptolemy completes his Almagest, which contains a catalog of stars, observations of planetary motions, and treatises on geometry and cosmology; c. 705 — Dunhuang Star Chart, a manuscript star chart from the Mogao Caves at Dunhuang
In 1979, the International Astronomical Union's 17th general assembly recommended that newly discovered star clusters, open or globular, within the Galaxy have designations following the convention "Chhmm±ddd", always beginning with the prefix C, where h, m, and d represent the approximate coordinates of the cluster centre in hours and minutes ...
A simple chart for classifying the main star types using Harvard classification In astronomy , stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors ...
Many globular clusters, such as the 13-Gyr old cluster M30 (pictured), are mass segregated. In astronomy, dynamical mass segregation is the process by which heavier members of a gravitationally bound system, such as a star cluster, tend to move toward the center, while lighter members tend to move farther away from the center.
A stellar association is a very loose star cluster, looser than both open clusters and globular clusters. Stellar associations will normally contain from 10 to 100 or more visible stars. An association is primarily identified by commonalities in its member stars' movement vectors, ages, and chemical compositions.
NGC 206 is the richest and most conspicuous star cloud in the Andromeda Galaxy, and is one of the largest and brightest star-forming regions in the Local Group. [2] It contains more than 300 stars brighter than M b =−3.6. [3] It was originally identified by Edwin Hubble as a star cluster but today, due to its size, it is classified as an OB ...
Thus, the lifetime of a star on the main sequence can be estimated by comparing it to solar evolutionary models. The Sun has been a main-sequence star for about 4.5 billion years and it will become a red giant in 6.5 billion years, [53] for a total main-sequence lifetime of roughly 10 10 years. Hence: [54]