Dec. 11 () –
The James Webb Space Telescope has detected a galaxy that existed only 600 million years after the Big Bang with a mass similar to that of our Milky Way at the same stage of development.
Other galaxies that Webb has detected in this period of the Universe’s history are significantly more massive. Nicknamed the Firefly Sparkle, This galaxy shines with star clusters (10 in total), each of which the researchers examined in great detail, in a new study published in Nature.
“I didn’t think it was possible to resolve a galaxy that existed so early in the Universe into so many different components, much less discover that its mass is similar to that of our own galaxy when it was in the process of forming,” he said. in a statement Lamiya Mowla, co-senior author of the paper and an associate professor at Wellesley College in Massachusetts. “There are so many things going on inside this small galaxy, including so many different phases of star formation.”
Webb was able to image the galaxy in sufficient detail for two reasons. One is a benefit of the cosmos: A massive foreground galaxy cluster radically enhanced the appearance of the distant galaxy through a natural effect known as gravitational lensing. And when combined with the telescope’s specialization in high-resolution imaging of infrared light, Webb provided unprecedented new data on the contents of the galaxy.
“Without the benefit of this gravitational lensing, we would not be able to resolve this galaxy,” said Kartheik Iyer, co-senior author and NASA Hubble Fellow at Columbia University in New York. “We knew we expected it based on current physics, but it’s surprising that we’ve actually seen it.”
Mowla, who saw the galaxy in Webb’s image, was attracted to its bright star clusters, because bright objects generally indicate that they are extremely lumpy and complicated. Because the galaxy looks like a “flash” or swarm of fireflies on a warm summer night, they named it the Spark of the Firefly galaxy.
IN THE ASSEMBLY PROCESS
The research team modeled what the galaxy might have looked like if its image had not been stretched by gravitational lensing and found that it resembled an elongated raindrop. Suspended within it are two star clusters towards the top and eight towards the bottom. “Our reconstruction shows that actively forming star clusters are surrounded by diffuse light from other unresolved stars,” Iyer said. “This galaxy is literally being assembled.”
Webb’s data show that the Firefly Spark galaxy is rather small, falling into the category of low-mass galaxy. It will take billions of years before it reaches its full weight and distinctive shape. “Most of the other galaxies that Webb has shown us are not magnified or stretched, and we cannot see their ‘building blocks’ separately. With Spark of the Firefly, we are witnessing a galaxy that is assembled brick by brick“Mowla said.
Because the image of the galaxy is warped into a long arc, the researchers easily identified 10 distinct star clusters, which emit most of the galaxy’s light. They are represented here in shades of pink, purple and blue. Those colors in the Webb images and their supporting spectra confirmed that star formation did not occur all at once in this galaxy, but it was staggered over time.
“This galaxy has a diverse population of star clusters, and it is remarkable that we can see them separately at such a young age of the Universe,” said Chris Willott of the National Research Council of Canada, co-author and principal investigator of the observing program. “Each group of stars is going through a different phase of formation or evolution.”
The projected shape of the galaxy shows that its stars have not settled into a central bulge or a thin, flattened disk, another proof that the galaxy is still forming.
Researchers can’t predict how this disorganized galaxy will form and shape over billions of years, but there are two galaxies that the team confirmed are “hanging” within a narrow perimeter and may influence how it forms. accumulates mass over billions of years.
Firefly Spark is only 6,500 light-years from its first companion, and its second companion is 42,000 light-years apart. To put it in context, the fully formed Milky Way is about 100,000 light years across – all three would fit within it. Not only are their companions very close, but researchers also believe they are orbiting each other.
Every time one galaxy passes another, the gas condenses and cools, allowing new stars to form in groups, which increases the mass of galaxies. “Galaxies in the early Universe have long been predicted to form through successive interactions and mergers with other smaller galaxies,” said co-author Yoshihisa Asada, a doctoral student at Kyoto University in Japan. “We could be witnessing this process in action.”
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