Webb offers another look at galactic collisions

September 18 () –

Infrared observations with the James Webb Space Telescope reveal a white and transparent bridge of stars taken from two galaxies that interact in a slow fusion process.

It is an elliptical galaxy and a larger spiral galaxy, collectively known as Arp 107, which is located 465 million light years from Earth in the constellation of Leo Minor.

This image is a composite combining observations from Webb’s Mid-InfraRed Instrument (MIRI) and Near-InfraRed Camera (NIRCam).

The MIRI data, depicted in orange-red, show regions of star formation and dust that is composed of soot-like organic molecules known as polycyclic aromatic hydrocarbons. MIRI also provides a snapshot of the large spiral’s bright core, home of a supermassive black hole.

The spiral galaxy is classified as a Seyfert galaxy, one of the two largest groups of active galaxies, along with galaxies that host quasars. Seyfert galaxies are not as luminous or as distant as quasars, making them better places to study similar phenomena in lower-energy light, such as infrared, ESA reportswhich Webb operates with NASA and the Canadian CSA.

This region is very similar to the Cartwheel Galaxy, one of the first interacting galaxies that Webb observed. Arp 107 may have turned out to be very similar in appearance to Cartwheel, but because the smaller elliptical galaxy had an off-center collision rather than a direct hit, the spiral galaxy got away with it and only its spiral arms were perturbed.

The collision isn’t as bad as it sounds. Although a lot of star formation was taking place before, collisions between galaxies can compress gas, improving the conditions needed for more stars to form. On the other hand, as Webb reveals, collisions also scatter a lot of gas, potentially depriving new stars of the material they need to form.