James Webb Space Telescope spies massive shockwave and baby dwarf galaxy in Stephan’s Quintet.

A shockwave traveling through Stephan’s Quintet at over a million miles per hour is causing turbulence in between its five galaxies.

The intergalactic medium, the flimsy clouds of warm-to-hot hydrogen plasma that exist in the space between galaxies, is being driven by bizarre phenomena brought on by a collision between the galaxies of Stephan’s Quintet and an invader galaxy.

Astronomers recently obtained a clear view of the intrusive galaxy NGC 7318b as it violently pushes its way into this group of galaxies at a relative speed of about 1.8 million mph thanks to new observations made with the James Webb Space Telescope (Webb or JWST) and the Atacama Large Millimeter/submillimeter Array (ALMA) (approximately 800 kilometers per second). With that speed, it would take less than 15 minutes to go from Earth to the moon and back.

This aggressive invasion of Stephan’s Quintet is causing a shockwave that is rippling across the interstellar plasma and establishing a “recycling plant” for warm and cold molecular hydrogen gas between the five galaxies. This shockwave is many times as huge as the Milky Way. In addition, scientists discovered a massive cloud of gas disintegrating into a less dense “fog” of warm gas. The JWST/ALMA images also revealed the possible collision of two clouds, the production of a tail of warm gas, and potentially the birth of a new galaxy.

The identification of these occurrences may further our knowledge of how turbulence affects the intergalactic medium, how collisions impact star formation, and how galaxies evolve in general.

Philip Appleton, the project’s lead astronomer and a senior scientist at Caltech’s Infrared Processing and Analysis Center (IPAC), said in a statement: “As this intruder crashes into the group, it is colliding with an old gas streamer that was probably caused by an earlier interaction between two of the other galaxies, and is causing a giant shockwave to form.”

We are observing unusual formations and the recycling of molecular hydrogen gas in the areas impacted by this violent activity, according to Appleton. “As the shockwave goes through this clumpy streamer, it is generating a very turbulent, or unsteady, cooling layer,” he added. Understanding molecular hydrogen’s fate can help us learn more about the history of Stephan’s Quintet and galaxies in general since it serves as the building block for stars.

The galaxies NGC 7317, NGC 7318a, NGC 7318b, NGC 7319, and NGC 7320 make up Stephan’s Quintet, which is a group of five galaxies about 270 million light-years away from Earth in the constellation Pegasus. The five galaxies have proven to be the perfect laboratory for researching galactic interactions, including dramatic collisions, and how these interactions affect the surroundings of the galaxies.

However, Stephan’s Quintet is unique from other galactic collision sites because, unlike other collision sites, these five galaxies are not experiencing the tremendous star creation that results from most galactic mergers. The turbulence caused by these galactic collisions, however, is felt in Stephan’s Quintet in the intergalactic medium since there isn’t enough material there to cause star creation.

This implies that star formation is not obscuring collision-triggered turbulence, giving astronomers an unobstructed glimpse of NGC 7318b as it swiftly fragments into Stephan’s Quintet.

Using ALMA, a 66-telescope astronomical interferometer in the Atacama Desert of northern Chile, Appleton and the colleagues took advantage of this chance to focus on three crucial locations of Stephan’s Quintet. The scientists’ observations enabled them to create the first ever precise depiction of how the hydrogen gas is continuously reshaped and transferred.

According to Joe Pesce, program officer for ALMA at the U.S. National Science Foundation, “the power of ALMA is clear in these data, giving astronomers with fresh insights and deeper knowledge of these previously unknown processes.”

Investigating three regions of turbulence  

A massive cloud of cold molecules is being dispersed and transformed into a tail of warm molecular hydrogen in the area known as Field 6 in the center of the main shockwave. The hydrogen is constantly recycled through the same temperature stages while the same processes occur.

Incredibly, the gas doesn’t survive the shock; instead, it just cycles through warm and cold phases, according to Appleton. “What we’re seeing is the disintegration of a massive cloud of cold molecules in a super-hot gas,” he said. Although we are still learning about these cycles, we may infer that the gas is being recycled since the tail is longer than the time it takes for the clouds it is formed of to dissipate.

These shockwaves are causing other weird phenomena outside only one hydrogen “recycling plant.” The researchers discovered two chilly gas clouds connected by a stream of warm molecular hydrogen gas in an area they named Field 5. This filament is being penetrated by a cloud with a bullet-like form, which is creating a ring-like structure.

According to Bjorn Emonts, a co-investigator on the study and an astronomer at the National Radio Astronomy Observatory (NRAO), “a molecular cloud-piercing through intergalactic gas, and leaving chaos in its wake, may be unusual and not yet fully understood.”

However, our results indicate that we have advanced in our knowledge of the startling behavior and tumultuous life-cycle of molecular gas clouds in Stephan’s Quintet.

Field 4 appears to be the most “normal” and calm of the regions the team has examined, with a less turbulent environment that has allowed hydrogen gas to collapse and result in the formation of a disk of stars. The group thinks that this heralds the birth of a young dwarf galaxy in Field 4.

In Field 4, it’s possible that pre-existing massive clouds of dense gas have become unstable as a result of the shock, and have collapsed to generate new stars as we anticipate, according to Pierre Guillard, a project co-investigator from the Institut d’Astrophysique de Paris in France. Even though Stephan’s Quintet’s shock wave has created as much cold molecular gas as our own Milky Way does, stars are still forming at a considerably slower rate than is typical.

Guillard thinks that these new results have profound effects on theories that describe how turbulence affects the cosmos. However, he said that further research would be required to fully comprehend the impact of high-level turbulence and how hot and cold gas combine.

Although the relationship between the cold, warm molecular, and ionized hydrogen gases in the wake of the massive shockwave was extensively studied using JWST images of Stephan’s Quintet in conjunction with ALMA observations, the team will need to turn to spectroscopic data to gain a more thorough understanding of the region.

However, Appleton said, “These new findings have finally shown us just how much we still don’t know.” “While we now have a better understanding of the gas structures and how turbulence contributes to their formation and maintenance, future spectroscopic observations will trace the motions of the gas through the doppler effect, tell us how quickly the warm gas is moving, enable us to measure the warm gas’s temperature, and show us how the gas is being cooled or warmed by the shockwaves. In essence, we just have one side of the narrative. It’s time to obtain the other now.”

The team’s findings were presented at the 241st meeting of the American Astronomical Society on Monday (Jan. 9). 

Source:SpaceCom

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