Astronomers Discover New Way to Weigh Planets Hidden Inside Dusty Disks

The dusty rings of newborn planets may hold the key to uncovering their mass, according to a team of researchers from the University of Warwick, MIT, and McMaster University, who are finally characterizing these previously obscured celestial objects . In a recent paper published in The Astrophysical Journal , the team reveals their novel method for extrapolating a newborn planet ’s mass from measurements of the dusty rings surrounding its host star , which prevent direct observation of the planet. These rings, known as protoplanetary disks , serve as breeding grounds for worlds, with their material eventually coalescing from dust into entire planets . Observing Protoplanetary Disks Advancements in observational technologies, such as the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, have allowed astronomers to take a closer look at protoplanetary disks, the rings of dust and gas that make up a host star’s planet-forming region. In those more detailed observations, astronomers have identified that these large disks are comprised of distinct ring structures. Researchers have suspected that these separate rings reveal something about the newborn planets already orbiting within the protoplanetary disk, yet have been unable to devise a method to interpret what they are seeing. “These bright rings are not just beautiful structures – they are essentially planetary fingerprints,” said lead author Amena Faruqi , PhD student, Astronomy and Astrophysics Group, University of Warwick. “We’ve long understood that the rings could be created from concentrated dust that piles up just beyond the orbit of young, embedded planets, but we’ve been so far unable to link features of these rings to planet masses.” “By reading ‘between the rings,’ we have now found a way to reconstruct the masses of the planets that create the rings, even when those planets are too faint or too embedded to observe directly,” Faruqi added. Modeling Newborn Planets The international team developed intricate computer simulations to model how varying planetary masses would influence the shape of dust rings within the protoplanetary disk. Analysis of the model revealed three essential clues in the rings for characterizing the planet that shaped it: the width, the amount of dust, and the brightest point. In particular, the brightest point in the ring held special significance, directly related to the planet’s mass and unaffected by external factors such as dust grain size or observational wavelength. According to the team, with just this one factor, researchers can identify the mass of a newborn planet obscured by a dusty disk, even without knowledge of the disk’s specific conditions. As a control, the team looked to one of the only systems whose planets have been directly imaged within their disk, PDS 70. Using their new technique based on the brightest point of five disks, the researchers arrived at a mass figure extremely close to those achieved in other mass estimates. “One of the strengths of this work is that it doesn’t stay in the realm of theory—we’ve been able to take these simulation results and apply them directly to real observed systems,” said co-author Dr. Jessica Speedie, 51 Pegasi b Postdoctoral Fellow, Massachusetts Institute of Technology. “Using the PDS 70 system as an observational laboratory in particular enabled a real verification of the approach, giving us confidence that these methods are genuinely ready to be applied widely as soon as possible.” What Hides in Protoplanetary Disks The team says their research lays the groundwork for identifying planets within disks in the future, either confirming suspected ones or revealing entirely new surprises, potentially even offering new insights into how our own Solar System formed. “Another striking result of the simulations is that, in typical discs, more massive forming planets can trap as much as 20 times the mass of Earth of dust within these rings,” said senior co-author Professor Emeritus Ralph Pudritz, Department of Physics and Astronomy, McMaster University. “This confirms ALMA observations – but raises the question of why new planets have not been detected in the trapped dust and pebbles of the ring.” Since these rings contain sufficient dust to initiate planet formation, the absence of any such formation within them will be an important focus of observations and astronomical theories moving forward. “This work gives observers a new practical toolkit for connecting what we see in dust rings directly to the masses of the planets creating them,” concluded senior co-author Dr. Farzana Meru, Reader, Department of Physics, University of Warwick. “What excites me most is the timing. With ALMA delivering increasingly detailed disk images, and future facilities on the horizon, there has never been a better moment to develop these methods.” The paper, “ Reading between the Rings: Observed Dust Ring Properties as Probes of Planet Masses ,” appeared in The Astrophysical Journal on May 28, 2026. Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at [email protected], and follow him on Twitter @mdntwvlf.