The Hubble astronomers have released an absolutely beautiful photo taken by the NASA/ESA Hubble Space Telescope of the jellyfish galaxy JO206.
In this Hubble image, the disk of the jellyfish galaxy JO206 is trailed by long tendrils of bright star formation that stretch towards the bottom right of the image, just as jellyfish trail tentacles behind them. The color image was made from separate exposures taken in the visible, ultraviolet and near-infrared regions of the spectrum with Hubble’s Wide Field Camera 3 (WFC3). The image is based on data obtained through six filters. The color results from assigning different hues to each monochromatic image associated with an individual filter. Image credit: NASA / ESA / Hubble / M. Gullieuszik / GASP Team.
Jellyfish galaxies are so-called because of their resemblance to their aquatic namesakes.
The tendrils of jellyfish galaxies are formed by the interaction between galaxies and the intracluster medium, a tenuous superheated plasma that pervades galaxy clusters.
As galaxies move through galaxy clusters they ram into the intracluster medium, which strips gas from the galaxies and draws it into the long tendrils of star formation.
The tentacles of jellyfish galaxies give astronomers a unique opportunity to study star formation under extreme conditions, far from the influence of the main disk of the galaxy.
“Understanding the physical conditions that lead to the formation of new stars, and conversely to the halting of the star formation activity, is central for astrophysics,” said Dr. Marco Gullieuszik from the INAF-Osservatorio astronomico di Padova and colleagues.
“Galaxy disks are the usual cradle for star formation. This is a hierarchical process traced by star-forming regions, dubbed clumps, which are ubiquitous in star-forming galaxies.”
“Extremely distant galaxies are dominated by bright clumps, which are larger and more massive than in the local Universe.”
“The star formation activity is strongly influenced and can be even halted by a number of processes, some of which are directly related to the environment in which the galaxy resides.”
“Ram pressure stripping, i.e. the removal of interstellar gas from the disk of star forming galaxies due to the hydrodynamical interaction with the hot intergalactic medium, is one such process.”
“This process is believed to have a strong impact on galaxy populations in dense environments such as galaxy groups and, especially, clusters.”
Dr. Gullieuszik and co-authors used Hubble to study star-forming clumps in JO206, a jellyfish galaxy located over 700 million light-years away from Earth in the constellation of Aquarius, and five other jellyfish galaxies.
They detected over 3,700 clumps in the disks, 1,200 clumps in the extraplanar regions, and over 1,200 clumps in the tails of these galaxies.
“Surprisingly, Hubble revealed that there are no striking differences between star formation in the disks of jellyfish galaxies and star formation in their tentacles, which suggests the environment of newly-formed stars has only a minor influence on their formation,” they said.
“Future works on the mass, age and star formation of the star-forming clumps, on trends and gradients with the distance from the galaxies and on their fate will elucidate how and how much these clumps differ from those in undisturbed galaxies, in order to shed light on the effects of ram pressure on the galactic interstellar medium and of environment on star formation.”
Their findings appear in two papers (paper #1 and paper #2) in the Astrophysical Journal.
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Marco Gullieuszik et al. 2023. UV and Hα HST observations of 6 GASP jellyfish galaxies. ApJ 945, 54; doi: 10.3847/1538-4357/acb59b
Eric Giunchi et al. 2023. HST imaging of star-forming clumps in 6 GASP ram-pressure stripped galaxies. ApJ, in press; arXiv: 2302.10615
