ESO’s VLT Survey Telescope (VST) at Paranal Observatory in Chile has taken the best ever photo of a concentration of galaxies known as the Fornax Cluster.
This VST image shows the central part of the Fornax Galaxy Cluster in great detail. Image credit: ESO / Aniello Grado / Luca Limatola.
The Fornax Cluster, also known as ACO S 373 or MCL 52, is located in the southern hemisphere constellation of Fornax.
Galaxy clusters do not come in neatly defined shapes so it is difficult to determine exactly where they begin and end. However, astronomers have estimated that the center of the Fornax Cluster is in the region of 65 million light-years from Earth. It is one of the closest of such clusters beyond our Local Group of galaxies.
The Fornax Cluster contains about 60 large galaxies, and a similar number of dwarf galaxies. Galaxy clusters like this one are commonplace in the Universe and illustrate the powerful influence of gravity over large distances as it draws together the enormous masses of individual galaxies into one region.
At the center of this particular cluster, in the middle of the three bright fuzzy blobs on the left side of the image, is NGC 1399, a so-called cD galaxy.
cD galaxies like NGC 1399 look similar to elliptical galaxies but are bigger and have extended, faint envelopes. This is because they have grown by swallowing smaller galaxies drawn by gravity towards the center of the cluster.
There is evidence that this process is happening before our eyes. Recent study has revealed a very faint bridge of light between NGC 1399 and the smaller galaxy NGC 1387 to its right.
This bridge, which is too faint to show up in this picture, is somewhat bluer than either galaxy, indicating that it consists of stars created in gas that was drawn away from NGC 1387 by the gravitational pull of NGC 1399. Despite there being little evidence for ongoing interactions in the Fornax Cluster overall, it seems that NGC 1399 at least is still feeding on its neighbors.
This image shows the Fornax Galaxy Cluster. The brightest galaxies are labeled. Image credit: ESO / Aniello Grado / Luca Limatola.
Towards the bottom right of the image is the large barred spiral galaxy NGC 1365.
This is a striking example of its type, the prominent bar passing through the central core of the galaxy, and the spiral arms emerging from the ends of the bar.
In keeping with the nature of cluster galaxies, there is more to NGC 1365 than meets the eye. It is classified as a Seyfert galaxy, with a bright active galactic nucleus also containing a supermassive black hole at its center.
