Nicknamed the Firefly Sparkle, the newly-discovered galaxy existed approximately 600 million years after the Big Bang and consisted of a least 10 star clusters.
The Firefly Sparkle galaxy is in the process of assembling and forming new stars, existed about 600 million years after the Big Bang, and weighs about the same as our Milky Way Galaxy if we could wind back the clock to see our Galaxy as it developed. Image credit: NASA / ESA / CSA / STScI / C. Willott, NRC-Canada / L. Mowla, Wellesley College / K. Iyer, Columbia.
The most distant galaxies detected are from when the Universe was around 5% of its current age.
However, these galaxies are around 10,000 times less massive than the Milky Way and their low mass makes them difficult to observe.
The Firefly Sparkle galaxy was first observed with the NASA/ESA Hubble Space Telescope, but new detailed observations from the NASA/ESA/CSA James Webb Space Telescope shed further light on the galaxy’s formation.
“I didn’t think it would be possible to resolve a galaxy that existed so early in the Universe into so many distinct components, let alone find that its mass is similar to our own Galaxy’s when it was in the process of forming,” said Dr. Lamiya Mowla, an astronomer at Wellesley College.
“There is so much going on inside this tiny galaxy, including so many different phases of star formation.”
Webb was able to image the Firefly Sparkle galaxy in sufficient detail for two reasons.
One is a benefit of the cosmos: a massive foreground galaxy cluster called MACS J1423.8+2404 radically enhanced the distant galaxy’s appearance through a natural effect known as gravitational lensing.
And when combined with the telescope’s specialization in high-resolution imaging of infrared light, Webb delivered unprecedented new data about the galaxy’s contents.
“Without the benefit of this gravitational lens, we would not be able to resolve this galaxy,” said Dr. Kartheik Iyer, an astronomer at Columbia University.
“We knew to expect it based on current physics, but it’s surprising that we actually saw it.”
The astronomers also observed two neighboring galaxies, which they name Firefly-Best Friend and Firefly-New Best Friend, located at 6,000 and 40,000 light-years from Firefly Sparkle, respectively, less than the size of the present day Milky Way.
Firefly Sparkle may be a young, gas-rich galaxy in its early formation stage, the authors propose.
They indicate the mass of Firefly Sparkle is concentrated in 10 clusters of stars, with a total mass of approximately 10 million times the mass of the Sun.
This makes Firefly Sparkle one of the lowest-mass galaxies resolved into star clusters observed at cosmic dawn, an epoch when galaxies were starting to form, with a mass similar to that of a progenitor Milky Way.
“It has long been predicted that galaxies in the early Universe form through successive interactions and mergers with other tinier galaxies,” said Yoshihisa Asada, a doctoral student at Kyoto University.
“We might be witnessing this process in action.”
“This is just the first of many such galaxies Webb will discover, as we are only starting to use these cosmic microscopes,” said Dr. Maruša Bradač, an astronomer at the University of Ljubljana.
“Just like microscopes let us see pollen grains from plants, the incredible resolution of Webb and the magnifying power of gravitational lensing let us see the small pieces inside galaxies.”
“Our team is now analyzing all early galaxies, and the results are all pointing in the same direction: we have yet to learn much more about how those early galaxies formed.”
The study was published in the journal Nature.
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L. Mowla et al. 2024. Formation of a low-mass galaxy from star clusters in a 600-million-year-old Universe. Nature 636, 332-336; doi: 10.1038/s41586-024-08293-0
Source : Breaking Science News