The close proximity of Stephan’s Quintet gives astronomers a ringside seat to galactic mergers and interactions.
NASA’s James Webb Space Telescope reveals never-before-seen details of the galaxy group called “Stephan’s Quintet” in an enormous new image. The close proximity of this group gives scientists a ringside seat to galactic mergers and interactions. Astronomers rarely see in so much detail how interacting galaxies trigger star formation in each other, and how the gas in these galaxies is being disturbed. Stephan’s Quintet is a fantastic “laboratory” for studying these processes fundamental to all galaxies. In a level of detail never seen before, the image also shows outflows driven by a supermassive black hole in one of the group’s galaxies. Tight galaxy groups like this may have been more common in the early universe when superheated, infalling material may have fueled very energetic black holes.
NASA’s Webb Sheds Light on Galaxy Evolution, Black Holes
Best known for being prominently featured in the classic Christmas film, “It’s a Wonderful Life,” Stephan’s Quintet is a stunning visual grouping of five galaxies. Now, NASA’s James Webb Space Telescope reveals Stephan’s Quintet in a new light. This gigantic mosaic is Webb’s largest image to date, covering about one-fifth of the Moon’s diameter. Constructed from almost 1,000 separate image files, it contains over 150 million pixels. The information from Webb provides new insights into how galactic interactions may have driven galaxy evolution in the early universe.
Webb shows never-before-seen details in this galaxy group thanks to its powerful, infrared vision and extremely high spatial resolution. Sparkling clusters of millions of young stars and starburst regions of fresh star birth grace the image. Sweeping tails of gas, dust, and stars are being pulled from several of the galaxies due to gravitational interactions. Most dramatically, the Webb Space Telescope captures huge shock waves as one of the galaxies, NGC 7318B, smashes through the cluster.
Together, the five galaxies of Stephan’s Quintet are also known as the Hickson Compact Group 92 (HCG 92). Although called a “quintet,” only four of the galaxies are actually close together and caught up in a cosmic dance. The fifth and leftmost galaxy, called NGC 7320, is well in the foreground compared with the other four. In fact, NGC 7320 resides just 40 million light-years from Earth, while the other four galaxies (NGC 7317, NGC 7318A, NGC 7318B, and NGC 7319) are around 290 million light-years away. This is still fairly close in cosmic terms, compared with more distant galaxies billions of light-years away. Studying such relatively nearby galaxies like these helps astronomers better understand structures seen in a much more distant universe.
This proximity provides scientists a ringside seat for witnessing the merging and interactions between galaxies that are so crucial to all of galaxy evolution. Rarely do astronomers witness in so much detail how interacting galaxies trigger star formation in each other, and how the gas in these galaxies is being disturbed. Stephan’s Quintet is an excellent “laboratory” for studying these processes fundamental to all galaxies.
Tight groups like this may have been more common in the early universe when their superheated, infalling material may have fueled very energetic black holes called quasars. Even today, the topmost galaxy in the group – NGC 7319 – harbors an active galactic nucleus, a supermassive black hole that is about 24 million times the mass of the Sun. It is actively pulling in material and puts out light energy equivalent to 40 billion Suns.
Webb studied the active galactic nucleus in great detail with the Near-Infrared Spectrograph (NIRSpec) and Mid-Infrared Instrument (MIRI). These instruments’ integral field units (IFUs) – which are a combination of a camera and spectrograph – provided the Webb team with a “data cube,” or collection of images of the galactic core’s spectral features.
The James Webb Space Telescope will use an innovative instrument called an integral field unit (IFU) to capture images and spectra at the same time. This video gives a basic overview of how the IFU works. Credit: NASA, ESA, CSA, Leah Hustak (STScI)
Much like medical magnetic resonance imaging (MRI), the IFUs allow scientists to “slice and dice” the information into many images for detailed study. Webb pierced through the shroud of dust surrounding the nucleus to reveal hot gas near the active black hole and measure the velocity of bright outflows. The telescope captured these outflows driven by the black hole in a level of detail that has never been seen before.
In NGC 7320, the leftmost and closest galaxy in the visual grouping, Webb was able to resolve individual stars and even the galaxy’s bright core.
As a bonus, Webb revealed a vast sea of thousands of distant background galaxies reminiscent of Hubble’s Deep Fields.
Combined with the most detailed infrared image ever of Stephan’s Quintet from MIRI and the Near-Infrared Camera (NIRCam), the data obtained by Webb will provide a bounty of valuable, new information. For instance, it will help astrophysicists understand the rate at which supermassive black holes feed and grow. Webb also sees star-forming regions much more directly, and it is able to examine emissions from the dust – a level of detail that was previously impossible to obtain.
Located in the constellation Pegasus, Stephan’s Quintet was discovered by the French astronomer Édouard Stephan in 1877.
The James Webb Space Telescope is the world’s premier space science observatory. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.
NASA Headquarters oversees the mission for the agency’s Science Mission Directorate. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages Webb for the agency and oversees work on the mission performed by the Space Telescope Science Institute, Northrop Grumman, and other mission partners. In addition to Goddard, several NASA centers contributed to the project, including the agency’s Johnson Space Center in Houston, Jet Propulsion Laboratory in Southern California, Marshall Space Flight Center in Huntsville, Alabama, Ames Research Center in California’s Silicon Valley, and others.
NIRCam was built by a team at the University of Arizona and Lockheed Martin’s Advanced Technology Center.
MIRI was contributed by ESA and NASA, with the instrument designed and built by a consortium of nationally funded European Institutes (The MIRI European Consortium) in partnership with JPL and the University of Arizona.
NIRSpec was built for the European Space Agency (ESA) by a consortium of European companies led by Airbus Defence and Space (ADS) with NASA’s Goddard Space Flight Center providing its detector and micro-shutter subsystems.