How Planets Are Formed

A Vassar astronomy professor is part of a team of scientists that has made a breakthrough discovery revealing how planets are formed. Colette Salyk, Associate Professor of Astronomy and Chair of Physics and Astronomy on the Maria Mitchell Chair, is one of more than 20 astronomers from North America, Europe, and Asia (known as the JDISCS team) analyzing data on planet formation that is being collected from the James Webb Space Telescope, launched in 2021. “One of our goals is to find young planetary systems that can form Earth-like planets,” Salyk said. “We’ve been gathering data for about a year and are focused on understanding how the chemistry in planet-forming regions influences the types and compositions of planets that eventually form.

Scientists have known for some time that solar systems are formed from large “proto-planetary disks” that orbit stars. The Webb telescope has provided this team with data from four such disks. During the early stages of planet formation, Salyk explained, icy pebbles about a centimeter in diameter are expected to move from the cold outer reaches of the planetary systems towards the warmer planet-forming regions, releasing water vapor as they heat up. Data from infrared light detected by the James Webb Space Telescope enabled Salyk and other members of the team to observe this transported water vapor in two of the disks—the two that also show evidence for the movement of pebbles. “This shows us that water can move around in planet-forming regions, carried by these pebbles. It was exciting for us to be able to confirm a theoretical idea that required the sensitivity of a telescope like JWST to actually see in action,” she said.

The JDISCS team will continue its work by analyzing dozens more disks in its sample to better understand planet-formation chemistry.

Salyk has secured a Space Telescope Science Institute (STScI) grant award for related research in collaboration with a colleague from the University of Wisconsin-Madison. The research is in support of a program titled “Building on ALMA: a James Webb Space Telescope (JWST) legacy survey of the chemical evolution of planet-forming disks.” As part of the project, they will combine JWST data and archival data from the Atacama Large Millimeter Array (ALMA) to study the evolution of chemical abundances across relevant disks. —Larry Hertz