The Hubble Space Telescope captured an image of a unique group of merging galaxies that provides a glimpse into processes in the early universe.
The five galaxies, known as the Hickson Compact Group (HCG) 40, are in the process of merging into a single entity, a process that will be complete roughly a billion years from now, Hubble officials said in a statement. The officials released the image in anticipation of the venerable telescope’s 32nd anniversary, which occurs on Sunday (April 24).
The image is part of the Hubble Space Telescope’s longstanding work in studying galactic evolution.
“Studying nearby groups like HCG 40 helps astronomers learn about how galaxies formed,” the Hubble team said. “Tight groups like this,” Hubble officials added of HGC 40, “may have been more common in the early universe when their superheated, infalling material may have fueled very energetic black holes called quasars.”
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The group, located some 300 million light-years away from Earth, is very tightly packed into a region of space less than twice the diameter of the stellar disk of our own galaxy, the Milky Way.
Although scientists have found more than 100 compact galaxy groups, according to the Hubble team, the configuration of HGC is rather unique as the galaxies are not part of a larger galaxy cluster, making them an interesting target for astronomers to study. How this configuration came into being is still a matter of debate.
“One possible explanation is that there’s a lot of dark matter — an unknown and invisible form of matter — associated with these galaxies,” Hubble officials wrote. “If they come close together, then the dark matter can form a big cloud within which the galaxies are orbiting. As the galaxies plow through the dark matter, they feel a resistive force due to its gravitational effects. This slows their motion and makes the galaxies lose energy, so they fall together.”
Studying the details of galaxies in nearby groups like this helps astronomers sort out when and where galaxies assembled themselves, and what they are assembled from, Hubble officials added.
The famed telescope launched on space shuttle Discovery on April 24, 1990 on a quest to better understand the early universe. Astronauts serviced the observatory five times, the last in 2009.
While Hubble is aging, including overcoming some serious “safe mode” incidents in 2021, the telescope remains healthy. NASA plans to pair Hubble’s work with the just-launched successor James Webb Space Telescope. Webb is in a months-long commissioning period set to finish around June.