A distant galaxy appears to have more than a dozen tightly packed star-forming clumps arranged like a bunch of grapes — far more than astronomers thought possible in a galaxy from the early universe.
The galaxy, nicknamed “Cosmic Grapes,” is believed to have formed just 930 million years after the Big Bang. A new study has revealed that the galaxy has at least 15 massive star-forming clumps in its rotating disk, forming what appears to be a bunch of bright purple grapes in space.
Using NASA’s James Webb Space Telescope (JWST) and the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers discovered the galaxy through a technique known as gravitational lensing, in which a foreground galaxy — in this case, an object known as RXCJ0600-2007 — serves as a magnifying glass for more distant objects.
“This object is known as one of the most strongly gravitationally lensed distant galaxies ever discovered,” study lead author Seiji Fujimoto, said in a statement from the University of Texas at Austin’s (UT Austin) McDonald Observatory.
“Thanks to this powerful natural magnification, combined with observations from some of the world’s most advanced telescopes, we had a unique opportunity to study the internal structure of a distant galaxy at unprecedented sensitivity and resolution,” added Fujimoto, who started the research while at UT Austin but is now at the University of Toronto.
The researchers collected more than 100 hours of telescope observations to study the primordial Cosmic Grapes galaxy. Earlier Hubble Space Telescope images of the object suggested a smooth, rotating disk, but the powerful resolution of ALMA and JWST revealed something juicier — the most detailed view yet of the galaxy’s inner structure and massive clumps of dense gas primed for star formation.
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“Our observations reveal that some early galaxies’ young starlight is dominated by several massive, dense, compact clumps rather than one smooth distribution of stars,” study co-author Mike Boylan-Kolchin, an astronomy professor at UT Austin, said in the same statement.
The discovery reshapes our understanding of early galaxy growth by revealing the first clear connection between a galaxy’s small internal structures — in this case, massive star-forming clumps — and its overall rotation, hinting that many seemingly smooth galaxies observed before may actually be filled with similar hidden clumps.
Their findings were published Aug. 7 in the journal Nature Astronomy.
