The arc surrounding the galactic pair is caused by gravitational lensing. Credit: NASA/ESA
Appearing like a cosmic pearl necklace against the blackness of space, the bright chain of young stellar superclusters captured by Hubble in the image above binds together two separate galaxies in the process of merging.
The two elliptical galaxies, both part of galaxy cluster [HGO2008]SDSS J1531+3414, have been observed before, but this is the first time that any clear evidence has been presented that the two celestial objects are in fact separate entities.
To find two elliptical galaxies merging, both rich enough in gas to encourage star formation between them is rare.
As a rule, galaxies in clusters are deprived of any significant amount of gaseous material.
The bridge of stars connecting the galaxies’ nuclei spans 100,000 lightyears (about the size of the Milky Way) and has clumped together in what is known as “beads on a string” star formation – a tightly bound mass of gaseous filaments interspersed with patches of new stars.
This too is another rare phenomenon.
The faint blue arcs that frame this galactic battle are an example of gravitational lensing, a result of the colossal forces produced by the merging galaxies capable of warping the space around it.