Free Astronomy Magazine March-April 2025

7 MARCH-APRIL 2025 form. Over time, the dust and gas in the disk will clump together, eventually forming planets, moons, and other celestial bodies. The disks won’t last forever — as a star ma- tures and planets form, the disk gradually disappears. So, what caused the unusual dissipation ob- served in the circumstellar disk of the secondary star? High-resolution ALMA imaging, combined with optical and infrared data from other telescopes, al- lowed researchers to study, analyze, and compare the stars’ properties and disks. This binary has a rela- tively small, tight orbit, which means gravity truncates the outer parts of the disk, but it is unlikely that the current binary orbit could alter the inner disk. Instead, other processes may be at work. “The dispersal of circumstellar disks is a complicated process with many unknowns. By looking at systems that form together, we can control one major variable: time. DF Tau and other systems in our survey tell us that disk evolution isn’t strictly a function of time; other processes are at play,” shares Taylor Kutra of Lowell Observatory, lead author of this research. Binary systems like DF Tau and other sources in this ALMA survey offer a natural laboratory to study how circumstellar disks evolve. Understanding these processes is essential for refining models of planet formation because disk evo- lution sets the timescale on which planet formation occurs. This research highlights the diver- sity of disk behaviors and under- scores the need for further studies to unravel the factors influencing their lifespans and structures. These findings deepen our understanding of binary star systems and shed light on the broader mechanisms shaping planetary systems across the galaxy. Lowell Observatory, combining data from the Atacama Large Mil- limeter/submillimeter Array (ALMA) and Keck Observatory, has unveiled intriguing findings about planet formation in this binary star system, known as DF Tau, along with other systems in this region. DF Tau consists of two young stars with nearly equal masses, orbiting each other every 48 years. Since both stars likely formed together, with the same composition in the same environment, astronomers would expect them to share differ- ent things in common, like having similar circumstellar disks. But this is not the case—while the brighter primary star has an active inner disk, the secondary star’s inner disk appears to have almost completely disappeared. These unexpected dif- ferences challenge current theories of disk evolution and planet forma- tion. Like a potter’s wheel shapes clay into various forms, a circum- stellar disk provides the materials and environment for planets to !