This is the deepest field image ever assembled of Abell 3667, a merging of 2 galaxy clusters 700 million light years away in the constellation Pavo. As with other deep fields, everything in the image is a galaxy, near or distant, except the objects with crossed X's, which are Milky Way stars in the foreground. This image was captured by the NOIRLab's Ground-Based Dark Energy Camera (DEC).
Of particular interest is the yellow glow of intracluster light from stars that have been stripped from their original galaxies by the intense gravitational interaction of the merging clusters. Intracluster light helps reveal the history of the cluster's formation and it's spatial distribution tracks that of the otherwise invisible dark matter around the cluster. (The new Vera C. Rubin Observatory will be producing millions of long exposure high resolution images of galaxy clusters that will further reveal intracluster light like this.)
In the second image posted, 2 galaxies in the field are showing the effects of ram pressure stripping. This happens because these galaxies are moving through the intracluster medium of the cluster creating a wind that causes their interstellar gas (not stars) to be stripped away and trail behind. In some cases, star formation occurs in this stripped material, but generally the process disrupts star formation in the moving galaxies. The pattern of extruding gas in one of the galaxies, J0171, makes it resemble a jellyfish, and galaxies like this are thus referred to as jellyfish galaxies.
Also visible in the the main image are faint bluish "galactic cirrus" or integrated flux nebulae from the high latitudes of our galaxy which also lie in the foreground. These nebulae are illuminated not by a single star, but by the combined output of radiation from all the stars in the Milky Way.
A high resolution version of this image (12,000 x 12,000 pixels) can be found here.
The news release with more discussion plus links to all the images and zoom and pan videos can be found here.
Image Credit: CTIO/NOIRLab/NSF/AURA Acknowledgment: PI: Anthony Englert (Brown University) Image Processing: T.A. Rector (University of Alaska Anchorage/NSF NOIRLab), M. Zamani & D. de Martin (NSF NOIRLab)
The text of this post was written by me, u/jerryosity.
https://www.reddit.com/gallery/1mm46a2