James Webb image shows two galaxies in the process of colliding

By Georgina Torbet Published September 18, 2024

A new image from the James Webb Space Telescope shows one of the universe’s most dramatic events: the colliding of two galaxies. The pair, known as Arp 107, are located located 465 million light-years away and have been pulled into strange shapes by the gravitational forces of the interaction, but this isn’t a purely destructive process. The collision is also creating new stars as young stars are born in swirling clouds of dust and gas.

The image above is a composite, bringing together data from Webb’s NIRCam (Near-InfraRed Camera) and MIRI (Mid-InfraRed Instrument). These two instruments operate in different parts of the infrared, so they can pick up on different processes. The data collected in the near-infrared range is seen in white, highlighting older stars and the band of gas running between the two galaxies. The mid-infrared data is shown in orange and red, highlighting busy regions of star formation, with bright young stars putting out large amounts of radiation.

If you look at just the MIRI data, below, you can see features like the glow of the supermassive black hole at the center of the galaxy to the right. Although the black hole itself can’t be seen directly, the swirling dust and gas around its event horizon heats up as it moves and glows brightly.

The swirls of star formation give this image a similar look to the Cartwheel Galaxy, which is also a galaxy undergoing an interaction. These interactions, or collisions, can reshape galaxies and have a complex relationship with the rate of star formation.

“The collision isn’t as bad as it sounds,” Webb scientists write. “Although there was much star formation occurring 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 disperse a lot of gas, potentially depriving new stars of the material they need to form.”

The Arp 107 pair will continue merging over hundreds of millions of years, eventually becoming one singular galaxy.