science & techESA/Hubble

A galaxy 800 million light-years away trails glowing tentacles of gas as it is stripped by a cluster

the gist

Hubble's image shows JW100, a galaxy about 800 million light-years away in the constellation Pegasus, whose streams of bright star-forming gas look like dangling tentacles. Astronomers call it a jellyfish galaxy. The tendrils form through ram pressure stripping, which happens when a galaxy moves through the hot diffuse gas filling a galaxy cluster. The gas acts like a headwind, pulling gas and dust from the galaxy's disc into trailing streams where new stars form. The image also shows IC 5338, a giant cD galaxy with two nuclei in the same cluster, which grew by absorbing smaller galaxies. The tendrils are observed to understand star formation under extreme conditions.

so what

Ram pressure stripping shows how a galaxy's environment can switch off or reshape its star formation, which is important for understanding how galaxies in clusters evolve.

ESA/Hubble · CC BY 4.0

Image: ESA/Hubble & NASA, M. Gullieuszik and the GASP team