(ORDO NEWS) — Looking at the first images of a well-known early galaxy taken by the James Webb Space Telescope (JWST), astronomers saw a clump of light near its outer edge.
Their original target was SPT0418-47, one of the brightest dusty star-forming galaxies in the early universe. Its distant light is bent and magnified by the galaxy’s gravity, forming a circle called the Einstein ring.
However, a deeper study of early JWST data led to the discovery that scientists have found a companion galaxy hidden behind the light of the foreground galaxy.
The age of the discovered galaxy is estimated at 1.4 billion years.
“We found that this galaxy has a superchemical abundance that none of us expected,” said astronomer Bo Peng, who led the data analysis.
The SPT0418-47 image revealed two new sources of radiation that are not part of the main galaxy. Scientists have determined that these were images of a companion galaxy.
The team calculated that the companion galaxy, which they named SPT0418-SE, was within 5 kiloparsecs of the ring. Such proximity suggests that galaxies inevitably interact with each other and possibly even merge.
The two galaxies are small in mass, like galaxies in the early universe, with SPT0418-SE being relatively less dusty, making it bluer. Its stellar mass is 7×109 solar masses.
The mass of the main galaxy is 1.2 x 1010 solar masses.
The most surprising thing about the companion galaxy was its mature metallicity. The team calculated that it is comparable to solar.
“We are seeing remnants of at least a couple of generations of stars that lived and died during the first billion years of the universe, which is not what we normally see,” Vishwas said.
“We hypothesize 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 nitrogen to oxygen ratio, since this ratio is a reliable indicator of how many generations of stars have lived and have died.”
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