M92

Messier 92 (M92) is a globular cluster in the northern constellation Hercules. It is among the brighter clusters in that region and can be observed with binoculars under favorable dark-sky conditions. Its apparent magnitude is about 6.2, and it spans roughly 14 arcminutes on the sky. It lies in the Milky Way's halo at an estimated distance of about 26,000–28,000 light-years from the Sun.

Discovered by Pierre Méchain in 1777, M92 was added to the Messier catalog by Charles Messier in 1781. It is also catalogued as NGC 6341.

M92 is an old, metal-poor cluster with an estimated age around 12–13 billion years and a metallicity [Fe/H] near −2.3, making it one of the more chemically primitive globular clusters in the Milky Way. It has a dense core and a relatively small half-light radius, characteristic of compact globular clusters.

In astronomical research, M92 serves as a benchmark for studying stellar evolution and dynamical processes in dense stellar systems, given its old age and low metallicity. Its color–magnitude diagram helps test theoretical models of low-metallicity stars, while measurements of its luminosity, motions, and structure contribute to understanding globular cluster formation and the Galaxy's assembly.

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