space Cosmic Scale

Astronomers spotted a rare galactic three-way where three galaxies are literally eating each other at the same time.

March 20, 2026

Original Paper

UGC 2369S: a Kpc Scale Triple Merger Candidate Identified in a Nearby Luminous Infrared Galaxy

Yuanze Ding, Michael J. Koss, Fiona A. Harrison, Charles C. Steidel, Connor Auge, Jared Gillette, Erica Hammerstein, Ruancun Li, Macon Magno, Ignacio del Moral-Castro, Alessandro Peca, Claudio Ricci, Yiqing Song, Ezequiel Treister, Zhuyun Zhuang

arXiv · 2603.18499

The Takeaway

While two galaxies crashing together is common, finding three distinct galactic cores merging simultaneously is incredibly rare. Observations show that in this chaotic three-way crash, the gravitational forces are so intense they are 'cannibalizing' the central bulge of stars from one of the participating galaxies.

From the abstract

We present high spatial resolution ($\lesssim$1.0''), multi-wavelength observations of UGC 2369S, a nearby luminous infrared galaxy showing three distinct cores separated on kpc scales in near-infrared (NIR) imaging with significant X-ray emission. Utilizing optical/NIR adaptive optics (AO), radio, \chandra X-ray, as well as archival HST imaging, we perform a comprehensive study of AGN activity, obscuration, and host properties. As one of the clearest cases of a triple-nucleus merger at $\simeq$