JLike us, galaxies often go through an awkward period during adolescence. Recent research has found that young galaxies collide and merge with other galaxies, creating lumpy, asymmetric “battle scars” and bursts of stellar activity. It takes billions of years for galaxies to stabilize and mature into the majestic spiral arm structures we are familiar with.
Or so we think.
Astronomers Rashi Jain and Yogesh Wadadekar were recently surprised to discover a relatively young galaxy in a primitive state, complete with spiral arms and more. Using deep imaging from the James Webb Space Telescope, they observed a galaxy that is strikingly similar to our own Milky Way from 13.6 billion years ago, but it formed just 1.5 billion years after the Big Bang, when the universe was only one-tenth its current age. They named the galaxy “Alaknanda” after one of the two sources of the Ganges River in India (the other is called “Mandakini”, the Hindi word for Milky Way). They published their findings Astronomy and Astrophysics.
Mature galaxies like ours have what’s known as a “grand design” spiral, two giant arms that spin outward from a center, and astronomers have long thought it would take billions of years to accumulate enough matter. Alakananda appears to have achieved this feat in record time.
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“The structural maturity of Alaknanda is tied to what we think of as galaxies that are billions of years old,” Jain explained in a statement. “Finding such a well-organized spiral disk in this era tells us that the physical processes that drive galaxy formation—gas accretion, disk subsidence, and possibly the development of spiral density waves—can operate more efficiently than current models predict. This forces us to rethink our theoretical framework.”
It is not only the shape of Alakananda that is surprising, but also its productivity. This precocious galaxy produces stars 20 times faster than the Milky Way, adding the equivalent of 60 suns per year. The discovery is changing our understanding of galaxy evolution and revealing what the early universe looked like.
“Arakananda reveals that galaxies in the early universe assembled much faster than we expected,” said Wadadekar. “Somehow, this galaxy managed to bring together 10 billion solar masses of stars in just a few hundred million years and organize them into a beautiful spiral disk. This is extremely fast by cosmic standards, and it’s forcing astronomers to rethink how galaxies form.”
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Main image: NASA/ESA/CSA, I. Labbe/R. Bezanson/Alyssa Pagan (STScI), Rashi Jain/Yogesh Wadadekar (NCRA-TIFR)
This story originally appeared on the Nautilus .
