NASA’s JWST captures stunning galaxy merger 250 million light-years away

A galactic dance and organic material

The image captured by the James Webb Space Telescope shows faint tidal tails, which are the result of material being pulled away from the galaxies due to gravity. This provides proof of the ongoing galactic merger. In addition, streams and filaments of organic material can be seen in a reddish-orange hue throughout Arp 220. This observation was made possible using Webb's Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI).

In Arp 220, the merging of two spiral galaxies has resulted in the creation of rotating, star-forming rings within each of its parent galaxy cores. These rings emit dazzling infrared light, which creates dominant diffraction spikes in the image.

Additionally, a densely packed, dusty area spanning about 5,000 light-years contains approximately 200 massive star clusters, with the gas concentration in this region equivalent to that of the entire Milky Way galaxy.

Webb’s capabilities and mission

The James Webb Space Telescope is a leading observatory in space science, designed to unravel puzzles within our solar system, explore remote planets orbiting other stars, and investigate enigmatic formations and beginnings of our universe, as well as our position in it. It is a collaborative effort among NASA, ESA (European Space Agency), and the Canadian Space Agency.

The James Webb Space Telescope's impressive depiction of Arp 220 showcases the breathtaking magnificence of the cosmos and the enigmatic phenomena that remain beyond our grasp. By utilizing Webb's advanced capabilities, researchers can scrutinize Arp 220 and other cosmic entities more comprehensively, which could enhance the comprehension of our position in the universe.

Study Abstract

The ultra-luminous infrared galaxy Arp 220 is a late-stage merger with several tidal structures in the outskirts and two very compact, dusty nuclei that show evidence for extreme star formation and host at least one AGN. New and archival high-resolution images taken by the Hubble Space Telescope provide a state-of-the-art view of the structures, dust, and stellar clusters in Arp 220. These images cover the near-ultraviolet, optical, and near-infrared in both broad- and narrow-band filters. We find that ∼ 90% of the Hα emission arises from a shock-ionized bubble emanating from the AGN in the western nucleus, while the nuclear disks dominate the Pβ emission. Four very young (∼ 3 − 6 Myr) but lower mass (<∼ 104 M) clusters are detected in Hα within a few arcsec of the nuclei, but produce less than 1% of the line emission. We see little evidence for a population of massive clusters younger than 100 Myr anywhere in Arp 220, unlike previous reports in the literature. From the masses and ages of the detected clusters, we find that star formation took place more-or-less continuously starting approximately a few Gyr ago with a moderate rate between ≈ 3 − 12 M yr−1 . Approximately 100 Myr ago, star formation shut off suddenly everywhere (possibly due to a merging event), except in the nuclear disks. A very recent flicker of weak star formation produced the four young, low-mass clusters, while the rest of the galaxy appears to have remained in a post-starburst state. Cluster ages indicate that the tidal structures on the west side of the galaxy are older than those on the east side, but all appear to pre-date the shutoff of star formation. Arp 220 has many of the characteristics expected of a ’Shocked Post-Starburst Galaxy’ or SPOG, since most of the system has been in a post starburst state for the past ∼ 100 Myr and the detected Hα emission arises from shocked rather than photo-ionized gas.