The Seeming Serenity of the Jellyfish Galaxy JW39

Monday - May 22 2023, 05:03 UTC - 1 year ago

The jellyfish galaxy JW39, located over 900 million light-years away in the Coma Berenices constellation, is a part of a hostile galaxy cluster and is exposed to intense gravitational forces and a hot plasma called intracluster medium. This leads to the process of ram-pressure stripping where the intracluster medium strips away gas and dust, creating trailing ribbons of star formation. Astronomers have found that star formation in the 'tentacles' of jellyfish galaxies is not significantly different when compared to the star-formation in the galactic disc.

The Jellyfish galaxy JW39, located in a hostile galaxy cluster, is exposed to intense gravitational forces and a hot plasma known as the intracluster medium. These conditions strip JW39 of its star-forming gas, creating trailing ribbons of star formation. However, research indicates that star formation in these ‘tentacles’ mirrors that in the main galaxy disc.

The jellyfish galaxy JW39 hangs serenely in this image from the NASA/ESA Hubble Space Telescope. This galaxy lies over 900 million light-years away in the constellation Coma Berenices, and is one of several jellyfish galaxies that Hubble has been studying over the past two years.

Despite this jellyfish galaxy’s serene appearance, it is adrift in a ferociously hostile environment; a galaxy cluster. Compared to their more isolated counterparts, the galaxies in galaxy clusters are often distorted by the gravitational pull of larger neighbors, which can twist galaxies into a variety of weird and wonderful shapes. If that was not enough, the space between galaxies in a cluster is also pervaded with a searingly hot plasma known as the intracluster medium. While this plasma is extremely tenuous, galaxies moving through it experience it almost like swimmers fighting against a current, and this interaction can strip galaxies of their star-forming gas.

This interaction between the intracluster medium and the galaxies is called ram-pressure stripping, and is the process responsible for the trailing tendrils of this jellyfish galaxy. As JW39 has moved through the cluster the pressure of the intracluster medium has stripped away gas and dust into long trailing ribbons of star formation that now stretch away from the disc of the galaxy.

Astronomers using Hubble’s Wide Field Camera 3 studied these trailing tendrils in detail, as they are a particularly extreme environment for star formation. Surprisingly, they found that star formation in the ‘tentacles’ of jellyfish galaxies was not noticeably different from star formation in the galaxy disc.