Galactic Groups and Clusters
Galactic Groups and Clusters
A "galactic group" is a collection of galaxies, typically fewer than 50, bound together by mutual gravity. Larger collections are called galaxy clusters and even larger structures being superclusters. Our own galaxy, the Milky Way, is part of the Local Group, which includes over 50 other galaxies.
This is an image of the M81 Group of galaxies, which comprises Bode's Galaxy (M81), Cigar Galaxy (M82), and The Garland Galaxy (NGC 3077).
Although Bode's and The Cigar are popular targets for astrophotographers, NGC 3077 is often overlooked. This peculiar galaxy is certainly worth a closer look. The galaxy is a disrupted elliptical galaxy probably as a result of gravitational interaction with its 2 larger neighbours. Its unique appearance is attributed to the presence of bright, young star clusters and nebulae scattered throughout its intertwined spiral arms, creating a garland-like effect.
Markarian's Chain is a stretch of galaxies that forms part of the Virgo Cluster. When viewed from Earth, the galaxies lie along a smoothly curved line. Charles Messier first discovered two of the galaxies, M84 and M86, in 1781. The other galaxies seen in the chain were discovered by William Herschel. It was ultimately named after the Armenian astrophysicist, Benjamin Markarian, who discovered their common motion in the early 1960s. Member galaxies include M84 (NGC 4374), M86 (NGC 4406), NGC 4477, NGC 4473, NGC 4461, NGC 4458, NGC 4438 and NGC 4435.Â
The bright members of the chain are visible through small telescopes. Larger telescopes can be used to view the fainter galaxies . Near the centre there appear the pair of interacting galaxies NGC 4438 and NGC 4435, about 50 million light-years away, known as Markarian's Eyes.
The Leo Triplet (also known as the M66 Group) is a small group of galaxies about 35 million light-years away in the constellation Leo. This galaxy group consists of the spiral galaxies M65, M66, and NGC 3628.
The Leo Quartet - also known as the Hickson 44 Compact Galaxy Group. NGC3190, NGC3187, NGC3193 and NGC3185.
The M105 cluster; comprising 5 galaxies; M95, M96, M105, NGC3384 and NGC3389; in the constellation of Leo.