Image Tour: Galaxy Cluster Abell 2744

Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with NASA’s Universe of Learning partners: Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, NASA Jet Propulsion Laboratory, and Sonoma State University

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 Text, Galaxy Cluster Abell 2744 Image Tour 

Fast Facts. Location, Constellation Sculptor. Distance from Earth, About 3.5 billion light-years. Size, About 5 million light-years across. Telescope, Hubble Space Telescope 

This cluster of galaxies is primarily known by its catalog number, Abell 2744, but it also has a more poetic name; Pandora's Cluster. The Hubble Frontier Fields Project imaged this region around the dense core of the galaxy cluster. 

Tour Stop, Galaxy Cluster. Not all galaxies in this image are part of the cluster. Astronomers have measured distances and confirmed these galaxies as members of Abell 2744. 

The entire cluster comprises thousands of galaxies, making it one of the largest known. 

Evidence indicates this giant cluster was formed by the merging of at least four smaller clusters. 

Tour Stop, Foreground/Background. All of the stars in this image are foreground stars within our Milky Way Galaxy. 

This galaxy is much closer to us than the cluster galaxies, and is also in the foreground. 

Many of the smaller galaxies are in the background behind the cluster 

The shapes and brightness of background galaxies can be changed by the massive cluster through an effect called "gravitational lensing." 

Tour Stop, Gravitational Lensing. Einstein's general relativity states that massive objects warp the space around them. Light that passes through warped space bends in a manner similar to passing through a glass lens. 

A yellow line bends around a glowing circle in the middle of a grid. 

Text, This deflection of light by mass is gravitational lensing. The light of a background galaxy is gravitationally lensed by Abell 2744. The background galaxy's appearance can become distorted, duplicated, and brightened. 

Tour Stop, Lensed Arcs. These streaks of light are background galaxies whose images have been highly stretched. 

Dozens of these "lensed arcs" appear throughout the region around the cluster. 

Tour Stop, Multiple Images. 

Gravitational lensing has created three images of the same background galaxy. The light from this galaxy has traveled three different paths through the warped space around the cluster. 

Tour Stop, Magnified & Brightened. Examining The faint details, astronomers discovered three images of a very distant galaxy. Located over 13 billion light years away, it is only observable because it has been magnified and brightened by lensing. 

In this manner, the galaxy clusters serves as an extra lens to extend Hubble's view into the depths of the universe 

Able 2744 is one of six massive galaxy clusters observed by the Frontier Fields Program. Studies of these clusters help astronomers understand dense galaxy environments, the effects of gravitational lensing, and the most distant galaxies that Hubble can observe. 

Galaxy Cluster, Foreground/Background, Gravitational Lensing, Lensed Arcs, Multiple Images, Magnified & Brightened