NASA’s Webb Digs into Structural Origins of Disk Galaxies

Above image credit: NASA, ESA, CSA, STScI, Takafumi Tsukui (ANU)

Present-day disk galaxies often contain a thick, star-filled outer disk and an embedded thin disk of stars. For instance, our own Milky Way galaxy’s thick disk is approximately 3,000 light-years in height, and its thin disk is roughly 1,000 light-years thick.

How and why does this dual disk structure form? By analyzing archival data from multiple observational programs by NASA’s James Webb Space Telescope, a team of astronomers is closer to answers, as well as understanding the origins of disk galaxies in general.

The team carefully identified, visually verified, and analyzed a statistical sample of 111 edge-on disk galaxies at various periods — up to 11 billion years ago (or approximately 2.8 billion years after the big bang). This is the first time scientists have investigated thick- and thin-disk structures spanning such vast distances, bridging the gap between observers probing the early universe and galactic archaeologists seeking to understand our own galaxy’s history.

“This unique measurement of the thickness of the disks at high redshift, or at times in the early universe, is a benchmark for theoretical study that was only possible with Webb,” said Takafumi Tsukui, lead author of the paper and a researcher at the Australian National University in Canberra. “Usually, the older, thick disk stars are faint, and the young, thin disk stars outshine the entire galaxy. But with Webb’s resolution and unique ability to see through dust and highlight faint old stars, we can identify the two-disk structure of galaxies and measure their thickness separately.”

(Source: webbtelescope.org)