Webb spots distant jellyfish galaxy

Astronomers using Webb reveal a jellyfish galaxy from about eight billion years ago, showing how gas loss shapes star formation in a trailing tail.

Webb finds a jellyfish galaxy in the distant past

Scientists using the James Webb Space Telescope have spotted COSMOS2020-635829, a jellyfish galaxy seen about eight billion years in the past at redshift 1.156. The galaxy shows a bright blue tail of gas and newly formed stars as it plows through the hot intracluster medium, a process known as ram pressure stripping. The tail reveals where the gas came from and how star formation can continue in the wake of a galaxy losing its fuel.

By capturing this rare object, Webb helps connect the distant universe with the present day. The discovery suggests that stripping plays a major role in quenching star formation in cluster satellites long before they fade, and that the star-forming knots in the tail can rival small local galaxies in their activity. The study also shows how combining Webb's infrared views with ALMA and other radio observations can map different gas phases as they are removed and recycled.

The find highlights how a galaxy’s life is shaped by environment. In crowded clusters, gas loss does more than dim a disk; it can spark new stars in stray gas and even form tiny dwarf-like clumps. That makes the study about more than one galaxy; it is about how clusters sculpt the whole population. It also underscores the value of looking at the same object with different kinds of light to test when and how quickly star formation is shut down.

The chase continues. Seeing gas and stars in infrared and radio wavelengths lets researchers test models of quenching and mass loss. Still, the sample is small and more galaxies need to be mapped across cosmic time. Webb’s ongoing surveys, together with ALMA and future arrays, will fill in the gaps and sharpen our theories.

Highlights

Future Webb observations may reveal how common jellyfish tails are across cosmic time.