The James Webb Space Telescope (JWST) has revolutionized our understanding of galaxy formation by providing unprecedented views of distant galaxies. A recent study published in the Monthly Notices of the Royal Astronomical Society has used JWST images to unlock a 10-billion-year mystery of how galaxies shape themselves.

Researchers have long known that many galaxies, including our own Milky Way, consist of two distinct parts: a thin disk and a thick disk. The thin disk contains younger, metal-rich stars, while the thick disk is composed of older, metal-poor stars. However, until now, these components had only been identified in nearby galaxies.

The study used 111 JWST images of distant edge-on galaxies to examine their vertical disk structures. This allowed researchers to observe how galaxies have built their disks over cosmic history. The findings revealed a consistent trend: in the earlier universe, more galaxies appear to have had a single thick disk, while in later epochs, more galaxies showed a two-layered structure with an additional thin disk component.

This suggests that galaxies first formed a thick disk, followed by the formation of a thin disk within it. In more massive galaxies, this thin disk appears to have formed earlier. The study estimated the thin disk formation time for Milky Way-sized galaxies to be around 8 billion years ago, aligning with formation timelines for the Milky Way itself.

The research team examined not only the stellar structure but also the motion of gas, direct ingredients of stars obtained from the Atacama Large Millimeter/submillimeter Array (ALMA) and ground-based surveys in the literature. These observations supported a coherent formation scenario: galaxies first formed a thick disk, followed by the formation of a thin disk within it.

The study hopes to bridge studies of nearby galaxies with far away ones and refine our understanding of disk formation. The findings provide valuable insights into galaxy evolution and answer one of the biggest questions in astronomy: was our galaxy’s formation typical or unique?

The universe has long been a mystery waiting to be unraveled. Recent discoveries have shed new light on one of its most fascinating phenomena: planet formation around young stars. Research led by Ayumu Shoshi and his team at Kyushu University and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) reveals that signs of planet formation may appear earlier than expected, providing a better understanding of this complex process.

The journey to form planets begins with protostars – stars still in the making. These nascent stars are surrounded by disks composed of low-temperature molecular gas and dust, known as protoplanetary disks. It’s within these disks that planets take shape. However, observing these early stages of planet formation directly is a challenge due to their distance from Earth.

The research team utilized improved data processing techniques to reanalyze archive data from the ALMA radio telescope. Their focus was on the Ophiuchus star-forming region, located 460 light-years away in the direction of the constellation Ophiuchus. The team produced high-resolution images of 78 disks, with more than half achieving a resolution over three times better than previous images.

The new images show striking patterns – ring or spiral shapes – in 27 of the disks, with 15 identified for the first time in this study. Combining these findings with previous work on another star-forming region, the team discovered that characteristic disk substructures emerge in disks larger than 30 astronomical units (au) around stars just a few hundred thousand years after they were born.

This groundbreaking research suggests that planets may begin to form at an earlier stage than previously believed, when the disk still possesses abundant gas and dust. In essence, planets grow together with their very young host stars, opening doors to new insights into the origins of our solar system and potentially habitable planets like Earth.

Astronomers have created a galactic masterpiece: an ultra-detailed image that reveals previously unseen features in the Sculptor Galaxy. Using the European Southern Observatory’s Very Large Telescope (ESO’s VLT), they observed this nearby galaxy in thousands of colors simultaneously. By capturing vast amounts of data at every single location, they created a galaxy-wide snapshot of the lives of stars within Sculptor.

“Galaxies are incredibly complex systems that we are still struggling to understand,” says ESO researcher Enrico Congiu, who led a new Astronomy & Astrophysics study on Sculptor. Reaching hundreds of thousands of light-years across, galaxies are extremely large, but their evolution depends on what’s happening at much smaller scales.

“The Sculptor Galaxy is in a sweet spot,” says Congiu. “It is close enough that we can resolve its internal structure and study its building blocks with incredible detail, but at the same time, big enough that we can still see it as a whole system.”

A galaxy’s building blocks — stars, gas and dust — emit light at different colors. Therefore, the more shades of color there are in an image of a galaxy, the more we can learn about its inner workings. While conventional images contain only a handful of colors, this new Sculptor Galaxy image is rendered in thousands of colors, revealing intricate details that would have been lost otherwise.

This extraordinary image not only showcases the beauty and complexity of the Sculptor Galaxy but also serves as a testament to human ingenuity and scientific curiosity. By pushing the boundaries of what we thought was possible with astronomical observations, researchers continue to expand our understanding of the cosmos and inspire new generations of scientists and space enthusiasts alike.

The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration for astronomy.

Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, Czechia, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner.

ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvelous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor.