Using the James Webb Space Telescope, astronomers have captured stunning images of galaxy mergers.
The merger of a large spiral galaxy and a smaller elliptical galaxy, known as Arp 107, is taking place 465 million light-years away from Earth in the constellation Leo Minor. The James Webb Space Telescope recorded images of Arp 107 using its Near Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI). With these instruments, James Webb discovered a nearly transparent white star bridge torn from both galaxies. Regions of star formation, consisting of gas and dust, appear in shades of orange and red, forming a smiley face shape among the stars.
The spiral galaxy involved in this merger is classified as a Seyfert galaxy, one of the largest groups of “active” galaxies that emit large amounts of energy from their centers.
Galaxy merger. (Image: NASA).
Named after American astronomer Carl K. Seyfert, Seyfert galaxies tend to be fainter than galaxies containing normal stars. This means that Seyfert galaxies are actually more accessible for study when using low-energy light, such as the infrared light that James Webb uses to observe the universe.
There are many similarities between Arp 107 and another group of interacting galaxies observed by James Webb – the Cartwheel galaxy. However, Arp 107 is not identical to Cartwheel. This is because the smaller elliptical galaxy within Arp 107 is offset during its collision with the larger spiral galaxy.
As a result, the spiral portion of Arp 107 has managed to retain most of its structure, except for the particularly distinctive spiral arms, which have been almost completely erased.
Galaxies of Arp 107 colliding as observed solely through the mid-infrared capabilities of the James Webb Space Telescope. (Image: NASA).
The collision between galaxies like Arp 107 can be a double-edged sword when it comes to star formation. In galaxies that are not actively forming stars, mergers can provide new gas reservoirs, components of star formation, and compress this gas into the dense state necessary for star birth. However, the downside, according to James Webb, is that collisions can disperse gas, causing galaxies to lose the material needed to form new stars.
The Arp 107 collision that the James Webb Space Telescope is observing is expected to take hundreds of millions of years to complete. When it concludes, the two galaxies will form a larger galaxy with an unusual shape.
