Produced by: Mohsin Shaikh
Astronomers using JWST found RUBIES-UDS-QG-z7, a massive galaxy that mysteriously shut off star formation just 700 million years after the Big Bang.
Holding over 10 billion solar masses in a region only 650 light-years wide, this compact relic has no young stars—only the red glow of ancient, dying ones.
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Andrea Weibel, a doctoral researcher at the University of Geneva, notes this galaxy quenched star birth shockingly early—defying decades of astrophysical models.
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Standard theories suggest galaxies take billions of years to grow and fade. This one upended that timeline by packing in mass and burning out in cosmic infancy.
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Using JWST's NIRSpec/PRISM tool, researchers detected no blue stars, only red ones—evidence the galaxy's youthful fire had long gone cold by the time its light reached us.
This find forces a crisis in simulations. “It’s more than 100 times more abundant than predicted,” says Weibel—suggesting early Universe galaxy evolution is far faster than believed.
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Dr. Anna de Graaff, principal investigator at Max Planck Institute, says this galaxy may be the ancient seed of today's giant elliptical galaxy cores.
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Astrophysicist Pascal Oesch from University of Geneva believes processes like black hole feedback and stellar winds may be behind such early quenching—still not fully understood.
Despite its age, RUBIES-UDS-QG-z7 resembles modern galaxy centers, hinting that today's galactic giants began forming far earlier than we ever imagined.