The Milky Way galaxy’s unique structure is revealed in a new study using data from the James Webb Space Telescope. Astronomers have analyzed 111 edge-on disk galaxies spanning nearly 11 billion years, tracing their evolution back to the early Universe.
According to researchers, most galaxies form a thick, older disk and then a thin, younger one. The Milky Way’s thick disk is 3,000 light-years high, while its thin disk is roughly 1,000 light-years thick. But when did this dual-layered structure form?
The James Webb Space Telescope has provided new insights into galaxy formation, allowing scientists to measure the thickness of disks at high redshifts (2.8 billion years after the Big Bang) for the first time. By analyzing data from the telescope, researchers found that galaxies tend to form their thick disk first, followed by a thin disk later on.
However, not all galaxies evolve at the same pace. Bigger, more massive galaxies started growing their thin disks around 8 billion years ago, while smaller galaxies didn’t begin until about 4 billion years ago. This timing difference could be related to the galaxies’ star-making efficiency.
The team’s findings support the ‘turbulent gas disk’ scenario of galactic evolution, which states that early galaxies were chaotic with turbulent gas sloshing around and collapsing into stars in a frenzy. As more stars formed, they began to stabilise the disk, forming the thin disk.
Astronomers say the timing of the thick-to-thin transition lines up with the formation of the Milky Way’s own thin disk. The James Webb Space Telescope has enabled scientists to uncover new insights into galaxy formation, shedding light on one of the universe’s biggest mysteries.
Source: https://www.skyatnightmagazine.com/news/webb-edge-on-disk-galaxies