An image captured by the James Webb Space Telescope shows Arp 107, a pair of interacting galaxies. The spiral galaxy UGC 5984 (or PGC 32620) and the elliptical galaxy MCG +05-26-025 (or PGC 32628) will eventually merge. The Arp 107 pair was already studied several times with various telescopes but the combination of the MIRI (Mid-Infrared Instrument) and NIRCam (Near-Infrared Camera) instruments allowed to capture many new details of the star formation activity triggered by the interaction between the two galaxies.
The top image (NASA, ESA, CSA, STScI) shows the Arp 107 pair seen in the near and mid-infrared by a combination of several filters of the James Webb Space Telescope’s MIRI and NIRCam instruments.
An image captured by the Hubble Space Telescope already showed the distortions already visible in the shape of the galaxy UGC 5984 with an arm that has become colossal. It’s a Seyfert galaxy, marked by an active galactic nucleus that doesn’t prevent the rest of the galaxy from being seen. That’s very useful in studying its interaction with MCG +05-26-025 and now allowed to obtain new details on the star formation in progress.
The interactions between galaxies have effects on the gas clouds present within them that depend on the type of influence on them. A cloud can be dispersed by gravitational interactions but if it’s compressed, a new phase of star formation is triggered within it.
In the case of the galaxy UGC 5984, the James Webb Space Telescope’s MIRI instrument allowed to see where the star formation is taking place, indicated by red-orange colors in the top image. There’s also dust composed of silicate molecules and organic molecules of the class of polycyclic aromatic hydrocarbons (PAHs), very common in space. MIRI also shows its bright nucleus, where there’s a supermassive black hole. That’s particularly visible in the bottom image (NASA, ESA, CSA, STScI) which shows only the results of observations conducted with the MIRI instrument.
The James Webb Space Telescope’s NIRCam instrument shows details of the stars inside both galaxies of the Arp 107 pair and the bridge of gas and stars that formed between them and now connects them, visible in white in the top image.
The Arp 107 pair is about 465 million light-years from Earth, far even for the James Webb Space Telescope to capture the details of the star formation processes that astronomers are always very interested in. Examining what’s happening remains useful for studying the consequences of galaxy mergers. These mergers are normal processes that take many millions of years to complete. For these reasons, the Arp 107 pair will continue to be observed and studied.
