Astronomers using the NASA/ESA Hubble Space Telescope have captured a stunning image of the unusual galaxy cluster ACO S520.
This Hubble image shows ACO S520, a collection of oval-shaped, elliptical galaxies some 3.4 billion light-years away in the constellation of Pictor. Image ctedit: NASA / ESA / Hubble / H. Ebeling.
Galaxy clusters are fundamental building blocks of the Universe, like stars and galaxies.
Typically, they contain thousands of galaxies of all ages, shapes and sizes.
They have a mass of about one million billion times the mass of the Sun and form over billions of years as smaller groups of galaxies slowly come together.
At one point in time galaxy clusters were believed to be the largest structures in the Universe — until they were usurped in the 1980s by the discovery of superclusters, which typically contain dozens of galaxy clusters and groups and span hundreds of millions of light-years.
However, clusters do have one thing to cling on to; superclusters are not held together by gravity, so galaxy clusters still retain the title of the biggest structures in the Universe bound by gravity.
“Galaxy clusters are among the largest known objects in the Universe, and studying these objects can provide insights into the distribution of dark matter, which is responsible for most of the mass of a galaxy cluster,” Hubble astronomers said in a statement.
“The vast masses of galaxy clusters is what causes many of them to act as gravitational lenses which distort and magnify light from even more distant objects.”
“This can allow astronomers to use galaxy clusters as a kind of natural gravitational telescope to reveal distant objects that would usually be too faint to resolve — even for the crystal-clear vision of Hubble.”
The galaxy cluster ACO S520, also known as PSZ1 G262.27-35.38, is located 3.4 billion light-years away in the constellation of Pictor.
“A menagerie of interesting astronomical finds fill the new Hubble image,” the astronomers said.
“As well as several large elliptical galaxies, a ring-shaped galaxy is lurking on the right of the image”
“A pair of bright stars are also visible at the left of this image, notable for their colourfl criss-crossing diffraction spikes.”
“This collection of astronomical curiosities is the galaxy cluster ACO S520.”
The new image of ACO S520 was made from separate exposures taken in the visible and near-infrared regions of the spectrum with Hubble’s Advanced Camera for Surveys (ACS).
Two filters were used to sample various wavelengths. The color results from assigning different hues to each monochromatic image associated with an individual filter.
“This is one of a series of Hubble observations searching for massive, luminous galaxy clusters that had not been captured by earlier surveys,” the researchers said.
“Appropriately, the proposal for observing time was named ‘They almost got away!’.”
“We took advantage of occasional gaps in Hubble’s busy schedule to capture images of these barely-explored galaxy clusters, revealing a wealth of interesting targets for further study with Hubble and the NASA/ESA/CSA James Webb Space Telescope.”
