This galactic collision made a blast brighter than 1 trillion suns

As two galaxies combine, they spur a frenzy of star formation.
 By 
Elisha Sauers
 on 
Webb telescope observing a galaxy collision
When two spiral galaxies merged, they ignited tremendous starbirth, creating this bright region known as Arp 220. Credit: NASA / ESA / CSA / STScI / Alyssa Pagan

The James Webb Space Telescope is observing what happens when two spiral galaxies crash into each other, and the result is something as bright as a trillion suns.

If that's a magnitude beyond comprehension, try thinking of it this way: The entire Milky Way galaxy has a luminosity on par with just 10 billion suns.

Scientists recently used the space observatory, a collaboration of NASA and the European and Canadian space agencies, to study the incredibly bright region about 250 million light-years away in the Serpens constellation. The object glows brightest in infrared wavelengths invisible to the naked eye, making it an ideal subject for Webb, which detects light in the infrared.


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The collision, known as Arp 220, is the brightest of the three closest galaxies to the Milky Way. That name derives from its being the 220th object among Halton Arp’s "Atlas of Peculiar Galaxies," a catalog of celestial oddities Caltech published in 1966.

Such a sharp, gleaming composite image demonstrates the $10 billion space telescope's ability to collect extraordinary data from the distant universe. Scientists believe Webb will spur a golden age in our understanding of the cosmos.

Researchers believe that as the two galaxies started combining about 700 million years ago, they ignited a rip-roaring burst of new stars. About 200 star clusters are within a dense, dusty region about 5,000 light-years across. The amount of gas found in this relatively small spot — just 5 percent the size of the Milky Way's breadth — is on par with all of the gas throughout our galaxy, according to the Space Telescope Science Institute in Baltimore.

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Such a phenomenon is known as a "ulirg" — an ultra-luminous infrared galaxy. Cosmologists have theorized that ulirgs could be catalysts in the evolution of elliptical, or egg-shaped galaxies in the universe, according to the European Space Agency.

Previously, radio telescopes saw 100 supernova, or star explosion, remnants in a section of Arp 220 spanning less than 500 light-years, and the Hubble Space Telescope discovered that the cores of its two parent galaxies are only 1,200 light-years apart.

But Webb's view provides even more detail on the intriguingly bright light source.

"Each of the combining galactic cores is encircled by a rotating, star-forming ring blasting out the glaring light that Webb captured in infrared," according to the institute in a post on April 17. "This brilliant light creates a prominent, spiked, starburst feature."

Topics NASA

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Elisha Sauers

Elisha Sauers writes about space for Mashable, taking deep dives into NASA's moon and Mars missions, chatting up astronauts and history-making discoverers, and jetting above the clouds. Through 17 years of reporting, she's covered a variety of topics, including health, business, and government, with a penchant for public records requests. She previously worked for The Virginian-Pilot in Norfolk, Virginia, and The Capital in Annapolis, Maryland. Her work has earned numerous state awards, including the Virginia Press Association's top honor, Best in Show, and national recognition for narrative storytelling. For each year she has covered space, Sauers has won National Headliner Awards, including first place for her Sex in Space series. Send space tips and story ideas to [email protected] or text 443-684-2489. Follow her on X at @elishasauers.

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