Astronomers have discovered a cluster of iron-rich stars in the early universe

Looking at the first images of the first known satellite taken by NASA’s James Webb Space Telescope (JWST), Cornell astronomers were intrigued to see a bright spot near its edge.

The first object of their focus, and the objective of the infrared survey, is SPT0418-47, one of the brightest, galaxies in the early universe, its distant light bends and grows with the force of the front of the galaxy in a circle , which is called the Einstein ring.

But a deeper dive into the first JWST data released last fall led to a surprising discovery: a satellite that was previously hidden behind the light of the first stars, which surprisingly seems to already be hosting an array of stars and much despite his age, which is estimated at 1.4. billion years.

“We found that this galaxy has a very high chemical composition, something none of us expected,” said Bo Peng, a doctoral student in astronomy who led the data analysis. “JWST is changing the way we look at this system and opens up new areas for studying how planets and stars formed in the early universe.”

Peng is the lead author of “Discovery of a Dusty, Chemically Mature Companion to the z~4 Starburst Galaxy in the JWST First Science Release,” published February 17 in Astrophysical Journal Letterswith eight co-authors who are current or former members of the Department of Astronomy in the College of Arts and Sciences.

The first images of a single Einstein ring taken by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile contain the signatures of a companion clearly resolved by JSWT, but cannot be interpreted as anything other than random noise, says Amit Vishwas, a research associate at the Cornell Center for Astrophysics and Planetary Sciences (CCAPS) and second author of the paper.

Analyzing the data embedded in each pixel of the images from JWST’s NIRSpec instrument, Peng discovered a new second source of light in the ring. He determined that the two new sources are images of a new galaxy that was used by using the same star that is responsible for creating the rings, although they are eight to 16 times larger—a testament to the power of the vision of infrared of JWST.

Further research into the chemistry of light has confirmed that strong emission lines from hydrogen, nitrogen and sulfur atoms show similar redshifts – a measure of how much light from the galaxy stretches into long, dense galaxies as it growing far away. This puts the two stars at about the same distance from Earth — calculated as a redshift of about 4.2, or about 10% of the age of the universe — and in the same region.

To confirm their findings, the researchers turned to previous ALMA observations. They found a line of ionized carbon gas consistent with the red shifts observed by JWST.

“That really destroyed him,” Vishwas said. “Because we have so many emission lines that have been changed in proportion, there is no doubt that this new galaxy is where we think it is.”

The team estimates the companion galaxy, which they named SPT0418-SE, is within 5 kiloparsecs of the ring. (The Magellanic Clouds, satellites of the Milky Way, are about 50 kilometers away.) This proximity suggests that the stars are bound to interact with each other and may merge, an observation that furthers our understanding of how the first stars formed. evolved into. the greatest.

The two stars are about as high in mass as galaxies in the early universe go, with the “SE” being the smallest and least dusty, making it appear bluer than the dust-covered ring. Based on the images of nearby stars with the same color, the researchers suggested that they could be “in a large dark galaxy with undiscovered neighbors.”

The most surprising thing about the satellite, considering its age and mass, is its high density – the amount of elements stronger than helium and hydrogen, such as carbon, oxygen and nitrogen. The team estimates that our sun, which is 4 billion years old, has inherited most of its metals from previous generations of stars that took 8 billion years to form.

“We see the remnants of at least two generations of stars that lived and died in the first billion years of Earth’s life, which is not what we see,” Vishwas said. “We hypothesize that the process of star formation in these stars must be efficient and start early in the universe, especially to explain the ratio of nitrogen to oxygen, because this ratio is a good measure of the number of generations stars. they lived and died.”

The researchers launched a proposal for JWST’s periodic observations to continue studying the ring and its companions and to reconcile the differences found between the visible spectrum and the far infrared.

“We are still working on this galaxy,” Peng said. “There is more research in this data.”

The team is grateful for the first science release that makes JWST data immediately available to the public, called TEMPLATES: Targeting Extremely Magnified Panchromatic Lensed Arcs and their Extended Star Formation, led by NASA astrophysicist Jane Rigby, project scientist research activities.