Columbia Professor’s Research Collaboration Shows That Planets Can Form Under Harsh Radiation

New observations from the Atacama Large Millimeter/submillimeter Array (ALMA),  an international astronomy facility, suggest that planet formation can occur even in harsh stellar environments previously thought to be inhospitable to it.

An international team of astronomers including Columbia professor Jane Huang used ALMA to capture high-resolution images of eight protoplanetary disks irradiated by intense ultraviolet light from a massive nearby star in the Sigma Orionis cluster in the Orion constellation. To their surprise, they found evidence of gaps and rings in most of the disks—structures commonly associated with the formation of giant planets, like Jupiter.

"We expected the high levels of radiation in this cluster to inhibit planet formation in the outer regions of these disks," said Columbia Astronomy Professor Jane Huang, lead author of a study on the findings. "But instead, we're seeing signs that planets may be forming at distances of tens of astronomical units from their stars, similar to what we've observed in less harsh environments."

Columbia postdoctoral fellow Shangjia Zhang was also a co-author on the study.

Previous studies had focused on disks in regions with low ultraviolet radiation. This new research provides the ALMA's highest resolution look at disks in a more extreme environment. "These observations suggest that the processes driving planet formation are quite robust and can operate even under challenging circumstances," Huang noted. "This gives us more confidence that planets may be forming in even more places throughout the galaxy, even in regions we previously thought were too harsh."

The findings have implications for understanding the formation of our own Solar System, which likely evolved in a similarly high-radiation environment. They also motivate future studies of disks in even more extreme stellar neighborhoods.

The research team used ALMA's most extended antenna configuration to obtain unprecedented detail in their disk images, achieving a resolution of about 8 astronomical units. This allowed them to resolve multiple distinct gaps and rings in several of the disks. While the exact nature of these disk structures is still debated, they are thought to be either conducive to planet formation or a consequence of interactions between forming planets and the disk material.

This study demonstrates the power of ALMA to probe planet formation in diverse environments across the galaxy. As astronomers build a more complete picture of how planets form under different conditions, they come closer to understanding the origins of Earth and the prevalence of planets around other stars.

This research was published in The Astrophysical Journal. It was supported by a grant from the National Science Foundation. This news story was adapted from a press release by the National Radio Astronomy Observatory.