JWST‘s original target was SPT0418-47, one of the brightest dusty, star-forming galaxies in the early universe. Because it is an extremely distant galaxy—it lies about 12 billion light-years from Earth—its light is bent and magnified by the gravity of another foreground galaxy (located between SPT0418-47 and the space telescope), creating a near-perfect circle called a Einstein call.
Using JWST, the astronomers were able to get a clearer view of SPT0418-47 and discovered a strange blob of light shining near the galaxy’s outer edge. As it turns out, the blob represents a companion galaxy that was previously overshadowed by the light from the foreground galaxy, according to a declaration (opens in new tab) from Cornell University.
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“We found that this galaxy was superchemically abundant, something none of us expected,” Bo Peng, lead author of the study and a doctoral candidate in astronomy at Cornell, said in the statement. “JWST is changing the way we see this system and opening up new places to study how stars and galaxies formed in the early universe.”
Previous observations of SPT0418-47 using Atacama Large Millimeter/submillimeter Array (ALMA) in Chile contained hints of the companion, which at the time were interpreted as random noise, the researchers said.
Using JWST, the researcher discovered that the companion galaxy, called SPT0418-SE, is within about 16,000 light-years of SPT0418-47. For comparison Magellanic Clouds — a few more dwarf galaxy companions The Milky Way – is located about 160,000 light years away from us.
The close proximity of SPT0418-47 and SPT0418-SE suggests that these galaxies are bound to interact or merge with each other finally. In turn, this galactic pair could shed light on how early galaxies evolved into larger galaxies, given SPT0418-47 is thought to have formed when the universe was only 1.4 billion years old, according to the statement.
Interestingly, SPT0418-SE is thought to have already hosted several generations of stars despite its young age. Both galaxies have a mature metallicity—or large amounts of elements like carbon, oxygen, and nitrogen that are heavier than hydrogen and helium—that resemble sun. But our sun is 4.5 billion years old and has inherited most of its metals from previous generations of stars that were eight billion years old, the researchers said.
“We see the remnants from at least a couple of generations stars having lived and died within the first billion years of the universe’s existence, which is not what we typically see,” study co-author Amit Vishwas, a research associate at the Cornell Center for Astrophysics and Planetary Sciences, said in the same statement.
“We speculate that the process of star formation in these galaxies must have been very efficient and started very early in the universe, especially to explain the measured abundance of nitrogen to oxygen, as this ratio is a reliable measure of where many generations of stars have lived and died,” said Vishwas.
The new results were published 17 Feb (opens in new tab) in Astrophysical Journal Letters.
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