From Star Dust to Planets (and Back Again): Tracing Worlds Across a Lifetime

In this white paper, Akke Corporaal and collaborators explore a sweeping question: How does dust, tiny solid particles found around stars, shape the formation, evolution, and survival of planets from a star’s birth to its death? The authors argue that dust-rich environments, from the discs around newborn stars to the winds of dying giants, form a continuous story linking stellar evolution and planet formation. Their goal is to show why understanding dust is essential to understanding how worlds like our own are made and transformed.

Planet Formation in Dusty Birth Environments

The paper begins by outlining the current state of the field. Planets and stars grow up together, and their histories influence one another in profound ways. Corporaal emphasizes that interactions between forming planets and the circumstellar discs they inhabit can carve out rings, gaps, and other structures, some of which have been seen in remarkable detail. Yet only a handful of protoplanets have been directly imaged so far, leaving astronomers to rely mostly on indirect evidence. Important processes, such as the role of the water snowline, a boundary in the disc where water vapor freezes into ice, remain difficult to observe even though they are thought to concentrate dust and jump-start planet formation. Current telescopes can study only the nearest and brightest young systems, leaving big gaps in our understanding of how planets form under different conditions.

Dust, Planet Survival, and the Late Stages of Stellar Evolution

The authors then turn to what happens later in a star’s life. As a low- or intermediate-mass star swells into a red giant branch (RGB) or asymptotic giant branch (AGB) star, its outer layers expand and are blown away in dusty winds. These outflows may be shaped by planets or brown-dwarf-like companions, raising questions about which planets survive engulfment and which meet destructive fates. Some evolved binary stars even host post-RGB/post-AGB discs, where dust collects into long-lived, structured systems reminiscent of young planet-forming discs. Corporaal notes that these could, in theory, be sites of second-generation planet formation, although none have been detected yet. Linking dust behavior across these evolutionary phases remains one of the field’s central open challenges.

Expected Advances in the 2030s

Looking ahead to the 2030s, major improvements in observational capabilities are expected. New instruments, such as upgrades to the Very Large Telescope Interferometer (VLTI) and future tools on the Extremely Large Telescope (ELT), will enhance astronomers’ ability to detect faint planets, study their atmospheres, and investigate dusty environments in galaxies like the LMC and SMC. Space missions such as PLATO will expand the census of planets orbiting both young and evolved stars. Yet even with these advances, many key processes, like dust grain growth, dust clumping, and subtle planet-disc interactions, will still occur on spatial scales too small for the coming generation of telescopes to resolve.

Prospects for the 2040s

The authors make their most ambitious case when discussing the 2040s. They argue that to truly unlock the physics of dust and its role in planet formation and survival, astronomy will need an infrared interferometric facility with baselines of at least one kilometer. Such an array would achieve angular resolutions around 0.1 milliarcseconds, fine enough to image regions only 0.01–0.1 astronomical units across, comparable to the distance between the Sun and Mercury, but in systems hundreds or thousands of light-years away. With this power, astronomers could finally observe snowlines, dust sublimation zones, migration traps, and small-scale disc structures in both young and evolved systems. They could also map dusty outflows, compare systems across a range of metallicities, and directly probe the environments where second-generation planets might arise.

Conclusion

The white paper concludes by emphasizing that building such capabilities would transform our understanding of how dust and planets influence one another over billions of years. By imaging these environments at unprecedented resolution, astronomers could test long-standing theories about planet formation, determine how planets are reshaped as their stars age, and clarify the full lifecycle of planetary systems across the Hertzsprung–Russell diagram. In Corporaal’s view, bridging stellar evolution and planet formation is not only possible, it is essential for telling the complete story of how worlds come to be.

Source: Corporaal