Indian scientists find galaxy like Milky Way from 12bn years ago
The galaxy – seen as it appeared when the Universe was just 1.5 billion years old – shows a mature, organised structure at a time when most early galaxies were believed to be irregular and chaotic, reports BBC.
Indian astronomers have identified a massive, well-structured spiral galaxy dating back nearly 12 billion years, a finding that researchers say challenges existing theories of galaxy formation.
The galaxy – seen as it appeared when the Universe was just 1.5 billion years old – shows a mature, organised structure at a time when most early galaxies were believed to be irregular and chaotic, reports BBC.
The discovery was made using the James Webb Space Telescope (JWST) by researchers Rashi Jain and Yogesh Wadadekar, who described the object as a "fully formed spiral galaxy" with distinct arms and a central bulge.
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Their study was published in the European journal "Astronomy and Astrophysics" in November.
Named "Alaknanda" after a Himalayan river, the galaxy was first spotted by Jain, a PhD candidate at the National Centre for Radio Astrophysics (NCRA-TIFR) in Pune, while analysing JWST images earlier this year. She said that out of nearly 70,000 objects she reviewed, only one displayed a grand-design spiral pattern.
The galaxy measures about 30,000 light-years across and shows the classic "beads-on-a-string" pattern – clusters of young stars arranged along its spiral arms – similar to features seen in nearby galaxies today.
Wadadekar said he was initially surprised by the observation. "It's astonishing that such a large galaxy with spiral arms existed just 1.5 billion years after the Big Bang," he told the BBC.
"To build up 10 billion solar masses of stars and form a stable disc so early is extremely rapid by cosmic standards," he added.
While Nasa estimates that the Universe contains hundreds of billions of galaxies, astronomers have long believed that those formed during the early cosmic dawn were small, turbulent and low in mass.
"But this galaxy stands out," Wadadekar said. "It's one-third the size of the Milky Way and forming stars 20–30 times faster than our galaxy does today."
