The Most Distant Fully-Formed Spiral Galaxy Known Has Been Spotted By JWST And it has an epic name. The James Webb Space Telescope (JWST) has once again made a groundbreaking discovery, spotting the most distant fully-formed spiral galaxy ever observed. This distant galaxy, nicknamed Zhúlóng, or “Torch Dragon,” is revolutionizing our understanding of galaxy formation in the early universe.
It has been just over three years since JWST was launched into space and in that time, the telescope has dramatically expanded our understanding of the distant universe. Among the important findings is the discovery of very young galaxies that already looked like their more senior counterparts in the local universe, and a recent study has shown a spiral galaxy that already had everything modern ones do just 1.13 billion years after the Big Bang. This discovery challenges previous theories about galaxy evolution.
Zhúlóng is a spiral galaxy like our own, the Milky Way. Zhúlóng also shows a clear division between its central concentration of stars, known as the bulge, and the disk where the spiral arms are located. As reported in a yet-to-be peer-reviewed paper, this is the most distant galaxy with a bulge, disk, and spiral arms known to date. The presence of these distinct structures so early in the universe is remarkable.
The bulge is believed to form first and for that reason, it has the older stars. Over time, the disk grows and the spiral arms form creating what we recognize and classify as a spiral galaxy. The observations of Zhúlóng show a clear distinction between the bulge and the disk – but that’s not all. The galaxy is also massive, weighing around 100 billion times our Sun (roughly what the Milky Way weighs today) having had over 13 billion years to grow. The sheer size and maturity of Zhúlóng are astonishing.
With this discovery, JWST demonstrates that the process of formation and evolution of spiral galaxies can happen in as little as a billion years, even though it likely took many other galaxies billions of years to get as big and with a morphology like the more modern spiral galaxies. Zhúlóng is forming stars at an impressive rate, much more prolific than our own galaxy. However, compared to similar massive galaxies at that time, it is pretty quiet. This rapid star formation is a key area of study.
Galaxies also grow through collisions with small and big galaxies. These mergers were a lot more common back in the past when the universe was denser. Still, it does not seem like the galaxy is undergoing anything like that now. If it had had mergers, the events would have been much quicker than they are today, leading to very efficient growth. The lack of observed mergers in Zhúlóng raises new questions about galaxy mergers and their role in galaxy development.
“How a morphologically mature galaxy that resembles nearby massive spirals can form in this environment remains an open question, but the discovery of this source is a first step and provides an important constraint on galaxy formation models,” the authors wrote in the paper. Zhúlóng’s existence challenges current models of galaxy formation.
The existence of Zhúlóng adds to the growing evidence that the way galaxies are born and grow in the formative years of the cosmos is far from understood. Even among massive galaxies from the time, Zhúlóng stands out. Maybe there is more than one way to build a big galaxy, or maybe there are slow and fast ways to build spirals. This discovery highlights the complexity of the early universe.
The team is planning to follow up with JWST and the Atacama Large Millimeter Array to understand this galaxy better, as well as to continue to discover more galaxy morphologies at these great distances from us. Future observations will help us unravel the mysteries of ancient galaxies and the cosmic dawn. This astronomy news is sure to excite anyone interested in the vastness and wonder of the universe.
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