Hubble Spots More Than Hundred Galaxies in Abell 209
Abell 209 is a group of massive galaxies located about 2.8 billion light years in the Constellation of Cetus.
This image Hubble shows Abell 209, a group of galaxies located at around 2.8 billion light years in the Constellation of Cetus. The color image includes both optical and infrared observations of the advanced Hubble camera for surveys (ACS) and wide camera 3 (WFC3). Twelve filters were used to sample various wavelengths. The color results from the allocation of different shades to each monochromatic image associated with an individual filter. Image credit: NASA / ESA / Hubble / M. Postman / P. Kelly.
Galaxies clusters contain thousands of galaxies of all ages, shapes and sizes.
As a rule, they have a mass of about a million billion times the mass of the sun.
At one point, the clusters of galaxies were considered the largest structures in the universe – until they were usurped in the 1980s by the discovery of superclusters, which generally contain dozens of clusters of galaxies and groups and cover hundreds of millions of light years.
However, the clusters of galaxies have something to hang on; Superclusters are not maintained together by gravity, so the clusters of galaxies still retain the title of the largest structures in the universe linked by gravity.
“The Galaxies of Abell 209 are separated by millions of light years, and the apparently empty space between the galaxies is in fact filled with hot and diffuse gas which can only be identified at wavelengths on X-rays,” said Hubble astronomers in a press release.
“An even more elusive occupant of this cluster of galaxy is dark matter: a form of matter which does not interact with light.”
“The universe is understood to be composed of 5% normal material, 25% dark matter and 70% dark energy,” they said.
“Hubble observations like those used to create this image can help us answer fundamental questions about our universe, including mysteries surrounding dark matter and black energy.”
“These investigations take advantage of the immense mass of a group of galaxies, which can bend the fabric of space-time itself and create distorted and enlarged images of galaxies and background stars in a process called gravitational lens.”
“Although this image is not the dramatic rings that the gravitational lens can sometimes create, Abell 209 always shows subtle lens signs at work, in the form of striated and slightly curved galaxies in the golden glow of the cluster.”
“By measuring the distortion of these galaxies, astronomers can map the distribution of the mass in the cluster, illuminating the underlying cloud of dark matter.”
“This information, that the fine resolution and the sensitive instruments of Hubble help to provide, is essential to test the theories of the way our universe has evolved.”
