NASA/ESA Hubble Space Telescope has captured an unusual discovery by imaging two elliptical galaxies merging into one and giving birth to chains of stars winding around the galaxies' nuclei.
At the center of the image captured lie two elliptical galaxies, part of a galaxy cluster known as [HGO2008] SDSS J1531+3414, which have strayed into each other's path. While this region has been observed before, this new Hubble picture shows clearly for the first time that the pair were two separate objects. However, they would not be able to hold on to their separate identities much longer, as they were in the process of merging into one.
Finding two elliptical galaxies merging was rare, but it was even rarer to find a merger between ellipticals rich enough in gas to induce star formation. Galaxies in clusters were generally thought to have been deprived of their gaseous contents; a process that Hubble had recently seen in action.
Nineteen compact clumps of young stars make up the length of this "string," woven together with narrow filaments of hydrogen gas. The star formation spans 100,000 light-years, which is about the size of our galaxy, the Milky Way.
The strand is dwarfed, however, by the ancient, giant merging galaxies that it inhabits. They are about 330,000 light-years across, nearly three times larger than our own galaxy. This is typical for galaxies at the center of massive clusters, as they tend to be the largest galaxies in the universe.
The electric blue arcs making up the spectacular egg-like shape framing these objects are a result of the galaxy cluster's immense gravity. The gravity warps the space around it and creates bizarre patterns using light from more distant galaxies.
Astronomers have ruled out the possibility that the blue strand is also just a lensed mirage from distant galaxies and now their challenge is to understand the origin of the cold gas that is fuelling the growth of the stellar superclusters.