NASA’s James Webb Space Telescope is discovering new galaxies that astronomers haven’t seen before in the early universe.
Astronomers recently pointed JWST to an object called MACS0647-JD. It is extremely far away and light takes time to travel, so looking at such a distant object is also looking into the past. MACS0647-JD is about 97% of the way to the Big Bang in the first 400 million years of the universe.
Space Telescope Science Institute researcher Dan Coe first discovered it 10 years ago with the Hubble Space Telescope, formerly NASA’s most powerful space observatory.
“With Hubble it was just this faint, red dot. We could tell it was really small, a small galaxy in the first 400 million years of the universe. Now we’re looking with Webb and we can resolve TWO objects,” Coe said in October. NASA release.
JWST is 100 times more powerful than Hubble, and its infrared lens allows it to peer further into the deep universe and distant past. Comparing the new JWST image with previous Hubble images, astronomers discovered new features of one of the oldest galaxies ever seen.
Both Hubble and JWST study the early universe through gravitational lensing. It occurs when a cluster of distant galaxies is so large that it bends space-time, bending the light from galaxies far behind it. This creates mirror images of the galaxies reflected back to us.
Thus, the trace of the mysterious MACS0647-JD system is visible in three points in the images above. The breaks in these three images of the JD system on the right show how clear the JWST images are. They clearly show two different objects.
“We’re actively debating whether these are two galaxies or two star clusters within a galaxy. We don’t know, but those are the questions that Webb has designed to help us answer,” Coe said.
The study has not yet been published, but the difference between the images is stark.
JWST can detect galaxy mergers and other unseen motions in the early universe
One of the objects is bluer, indicating that relatively young stars formed within it. The other is redder, indicating an older object with more interstellar dust.
“We may be witnessing a merger of galaxies in the very early universe. If this is the most distant merger, I’ll be really ecstatic,” Tiger Yu-Yang Hsiao, a doctoral student who studied the images with Coe, said in a NASA release.
JWST is likely to detect galaxies even further away from the beginning of the universe. This will help scientists piece together the lost history of the first 400 million years.
“Until now, we haven’t been able to study galaxies in the early universe in great detail. Before Webb, we had dozens of galaxies. Studying them can help us understand how they evolved into galaxies like the one we live in today. And how the universe has evolved over time,” Rebecca Larson, another doctoral student who studied the images, said in a NASA statement.
He pointed to all the other tiny dots in the new JWST image — each one a distant galaxy.
“The amount of information we haven’t been able to see before is amazing,” he said, adding, “And it’s not a deep field. It’s not a long exposure. We’ve tried to use this telescope to look at one point for a really long time. This is just the beginning!”
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