‘Firefly Sparkle’: Nasa’s James Webb telescope finds tiny Milky Way-like galaxy

Nasa’s

James Webb Space Telescope

has discovered a galaxy from the early universe, offering a rare look at how galaxies like the Milky Way may have formed.
The galaxy, known as “Firefly Sparkle” for its shining

star clusters

, dates back to 600 million years after the Big Bang, when the universe was only 5 per cent of its current age.
“Webb discerned distinct star clusters in the

Firefly Sparkle galaxy

, which existed 600 million years after the big bang – the first discovery of an actively forming galaxy as lightweight as the young Milky Way,” Nasa’s Webb telescope handle posted on its X account.

The galaxy gets its nickname from its appearance in Webb’s images. “A group of fireflies—which is what this galaxy looks like—is called a sparkle,” Lamiya Mowla, an assistant professor at Wellesley College, was quoted as saying by news agency Reuters.
Mowla is the co-lead author of the paper “Formation of a Low-Mass Galaxy from Star Clusters in a 600-Million-Year-Old Universe,” published in the journal Nature.
Mass equal to 10 million suns

Firefly Sparkle, estimated to have a mass equal to 10 million suns, is one of the earliest

low-mass galaxies

discovered and has two other relatively small galaxies as neighbors, named Firefly-Best Friend and Firefly-New Best Friend.
Unlike other galaxies from this period, which tend to be significantly larger, this galaxy’s small size and lightweight nature make it a rare find. Its visible portion spans just 1,000 light-years—a fraction of the Milky Way’s 100,000 light-year diameter.
The galaxy contains 10 star clusters spread across a long arc of stars. Researchers noted that these clusters represent different stages of star formation. “This galaxy has a variety of star clusters, and it’s amazing that we can see them clearly so early in the universe’s history,” Chris Willott, another author of the paper, was quoted as saying by Nasa.
Gravitational lensing
Webb captured detailed images of Firefly Sparkle due to gravitational lensing, a phenomenon where a massive galaxy cluster bends and magnifies light from objects behind it. This magnified the galaxy’s light by 16-26 times, making its features visible. “Without this lensing effect, we couldn’t see the galaxy,” Kartheik Iyer, co-lead author and Nasa Hubble Fellow at Columbia University, was quoted as saying by Nasa.
The galaxy’s uneven shape, resembling an elongated raindrop, suggests it is still forming. “Most of the galaxies Webb has shown us aren’t stretched or magnified, so we can’t see their ‘building blocks’ separately. With Firefly Sparkle, we’re seeing a galaxy being built piece by piece,” said Mowla.
Milky way ancestor
The discovery of Firefly Sparkle gives scientists a glimpse of what the Milky Way may have looked like in its early years. Researchers found that the galaxy’s mass matches what would be expected for an early Milky Way ancestor. “This observation lets us see what galaxies like our Milky Way might have looked like when they were young,” Mowla said.
Each star cluster in Firefly Sparkle shows slight colour differences, suggesting stars formed at different times. Younger, hotter stars appear blue, while older stars look red. “It’s fascinating to see how different stages of star formation exist together in such a small galaxy,” Mowla said.
‘Firefly-Best Friend’ and ‘Firefly-New Best Friend’
Firefly Sparkle is accompanied by two smaller galaxies, called ‘Firefly-Best Friend’ and ‘Firefly-New Best Friend’. They are located 6,500 and 42,000 light-years away, respectively.
All three galaxies could easily fit inside the Milky Way, Nasa said. Researchers think their interactions could affect Firefly Sparkle’s growth. Each time one galaxy passes another, gas condenses and cools, allowing new stars to form in clumps, adding to the galaxies’ masses. “It has long been predicted that galaxies in the early universe form through successive interactions and mergers with other tinier galaxies,” Yoshihisa Asada, a doctoral student at Kyoto University, was quoted by Nasa,
History of galaxy formation
The findings support existing theories about early galaxy formation. Dense gas clouds in the young universe likely collapsed to form star clusters, which merged over time to create larger galaxies.
“Current theory and simulations suggest several possible mechanisms for how stars form from gas in the extreme conditions of the early universe,” Iyer said. “Our analysis shows these galaxies build up through the formation of massive star clusters in regions of extreme pressure and density,” he added.