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The Webb Space Telescope has captured a record-breaking image of stars in the Dragon’s Arc, a spiraling spiral of a galaxy in the distant universe.
The galaxy is 6.5 billion light-years from Earth and Webb’s recent snapshot captures 44 individual stars, seen thanks to the telescope’s remarkable capabilities and the fortuitous arrangement of objects between the telescope and the galaxy. Let’s explain.
The Dragon’s Arc is just that – a curved strip of light in space – because its light is flattened by the gravity of the intervening objects. Those objects that intervene are gravitational lenses, which bend and cool the light from more distant objects, magnifying it to an observer (in this case, the Webb space telescope).
Lens within a lens
In a recent study, a group of astronomers scrutinized Webb’s observations of a galaxy cluster and a well-known gravitational lens known as Abell 370. The cluster has magnified distant stars about 100 times, and one star in the cluster has act as a lens in it. lens, making distant stars come into sharper relief. The research of the team describing the target stars was published this week in Astronomy of nature.
“Inside galaxy clusters, there are many stars floating around that are not bound by any galaxies,” said Eiichi Egami, a research professor at the Steward Observatory and co-author of the paper, in a Arizona State University. liberation. “When one of them passes in front of the background star in the distant galaxy along the line of sight with Earth, it acts like a microlens, in addition to the microlensing effect of the galaxy cluster as a whole.”
New possibilities
Lensception, if you will, allowed the research team to pick out individual stars that would otherwise be too fuzzy to make out. The team studied the stars and concluded that “many of them are consistent with red giants or supergiants magnified by factors of hundreds”, as the group wrote in the paper.
“This groundbreaking discovery demonstrates, for the first time, that studying a large number of individual stars in a distant galaxy is possible,” said Fengwu Sun, a researcher at the Center for Astrophysics | Harvard & Smithsonian, in release.
Such red stars are near the end of his life. As stars use up their fuel, they swell up and expel reams of gas and dust. Webb is no stranger to these ancient stars; in 2022 and 2023, the leading observatory trained its eye on Earendel, the most distant known star, and found signs that ancient gas ball may have a partner in crime.
Discovering a single distant star is remarkable in itself. In November 2024, astronomers have caught first detailed image of a star outside our galaxy – a red supergiant in its final stages of life. But a whole collection of stars is more scientifically useful. As the team wrote, the work showed that “observations from the Webb Space Telescope could lead to the possibility of making statistical studies of stars at high-redshift”.
Astronomers will conduct follow-up observations of the arc with the Webb telescope, which are expected to reveal more of the magnified stars in the distorted galaxy. In addition to helping scientists understand how different gravitational lenses magnify ancient light, the results could reveal aspects of dark matter.
