Astronomers from Yale University, led by Harrison Souchereau and Jeffrey Kenney, have observed a unique 'jellyfish' galaxy, NGC 4858, within the Coma Cluster, located over 300 million light-years away. This barred spiral galaxy is providing new insights into galactic dynamics within one of the universe's most extreme environments.
The distinctive 'jellyfish' appearance of NGC 4858 is due to ram pressure stripping. As the galaxy moves through the cluster, the extreme pressure of the intracluster medium (ICM) strips away its internal gas, creating long trails of gas and young stars, resembling jellyfish tendrils. High-resolution images from the ALMA radio telescope revealed not only the jellyfish shape but also 'bunny ears,' distorted spiral arm features.
The 'bunny ears' are likely a result of the environmental wind combined with the galaxy's rotation. The team also found evidence of gas being pushed out of the galactic disk and then falling back. These findings offer a clearer understanding of how galaxies evolve in dense environments and the impact of ram pressure on star formation. The study was published in June 2025.