Streams of star-forming gas dripping from the disk of a spiral galaxy called JW100 are formed by a process called ram pressure stripping, and their resemblance to dangling tentacles has led astronomers to refer to such objects as jellyfish galaxies.
This Hubble image shows the jellyfish galaxy JW100 (seen edge-on in the lower right). Image credit: NASA / ESA / Hubble / M. Gullieuszik / GASP Team.
Early 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 and it is believed to have a strong impact on galaxy populations in dense environments such as galaxy groups and, especially, clusters.
“Ram pressure stripping occurs when galaxies encounter the diffuse gas that pervades galaxy clusters,” Hubble astronomers said in a statement.
“As galaxies plough through this tenuous gas it acts like a headwind, stripping gas and dust from the galaxy and creating the trailing streamers that prominently adorn JW100.”
JW100 is located approximately 800 million light-years away in the constellation of Pegasus.
This galaxy is a member of the large galaxy cluster Abell 2626 (A2626).
“The bright elliptical patches in this image are other galaxies in Abell 2626,” the astronomers said.
“As well as JW100’s bright tendrils, the image also contains a remarkably bright area of diffuse light towards the top of this image which contains two bright blotches at its core.”
“This is the core of IC 5338, the brightest galaxy in Abell 2626, known as a cD galaxy.”
“It’s not unusual for cD galaxies to exhibit multiple nuclei, as they are thought to grow by consuming smaller galaxies, the nuclei of which can take a long time to be absorbed.”
“The bright points of light studding its outer fringes are a rich population of globular clusters.”
The color image of JW100 was made from separate exposures taken in the visible, near-infrared and ultraviolet regions of the spectrum with Hubble’s Wide Field Camera 3 (WFC3).
Six filters were used to sample various wavelengths. The color results from assigning different hues to each monochromatic image associated with an individual filter.
“This observation is part of a sequence of observations designed to explore star formation in the tendrils of jellyfish galaxies,” the researchers said.
“These tendrils represent star formation under extreme conditions, and could help us understand the process of star formation elsewhere in the Universe.”
The findings appear in two papers 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
