Imagine peering into the cosmic nursery, where newborn planets are still cocooned in dusty blankets, hidden from our view. But what if these planetary infants start stirring much earlier than we thought? This is the tantalizing question at the heart of groundbreaking research using the Atacama Large Millimeter/submillimeter Array (ALMA), a telescope so powerful it can pierce through the dusty veils shrouding young stars. ALMA has already gifted us with stunning images of protoplanetary disks—the swirling cradles of planets—complete with gaps and rings carved out by these celestial newborns. Now, a team of astronomers has used ALMA to image 16 disks around the youngest, most primitive stars, known as Class 0/1 protostars, and their findings are shaking up our understanding of planet formation.
In a study soon to be published in Astronomy & Astrophysics under the title "FAUST. XXVIII. High-Resolution ALMA Observations of Class 0/I Disks: Structure, Optical Depths, and Temperatures," researchers reveal that planets might begin their formation journey much earlier than previously believed. Led by Dr. Maria Jose Maureira Pinochet, an Astronomy Postdoc at the Max Planck Institute for Extraterrestrial Physics, the study is part of the Fifty AU STudy (FAUST), an ambitious program using ALMA to explore the earliest stages of star and planet formation. The research is currently available on the arXiv preprint server (https://arxiv.org/abs/2510.19635).
But here's where it gets controversial: Traditionally, astronomers thought planet formation was a sequel to star formation. However, mounting evidence suggests that planets might start taking shape while the star itself is still a protostar, deeply embedded in its dusty, gaseous envelope. "Growing evidence indicates that planet formation kicks off during the embedded protostellar stages (Class 0/I)," the authors write, "making the study of protostellar disks crucial for understanding both the protostar's growth and the initial phases of planet formation."
Observing these protostellar disks is no easy feat. The thick gas and dust obscure the action, but ALMA's capabilities have allowed researchers to glimpse 16 of these incredibly young systems. "These baby disks are the missing link between the collapsing cloud and the later stages of planet formation," explains Paola Caselli, Director at the Center for Astrochemistry at MPE and a key author of the study. "They help us understand how stars and planets emerge together."
While the resolution of such observations has improved, there's still much to uncover. One goal is to pinpoint when disk substructures—like those seen in more evolved Class II disks—first appear in Class 0/1 disks. So far, astronomers have examined nearly 60 Class 0/1 disks, but only five show clear substructures, all in Class 1 disks. And this is the part most people miss: This could mean either that planet formation begins during the Class I stage or that younger disks are too optically thick to reveal their substructures clearly.
The researchers identified only one definite substructure, previously known, and one potential new one. But don't dismiss their findings as insignificant. The nature of these substructures hints that many more are lurking just beyond ALMA's current reach. "Our results suggest that annular substructures can form as early as the Class 0 stage but are often hidden by thick emissions," the authors note.
Beyond this, the study reveals that these young disks are about 10 times brighter than more evolved ones, primarily due to their thickness and mass—far greater than previously estimated. The findings also shed light on the forces shaping these disks, with self-gravity and accretion heating playing pivotal roles. "These processes influence both the mass available for planet formation and the chemistry leading to complex molecules," adds Hauyu Baobab Liu from the National Sun Yat-sen University in Taiwan.
Nature, it seems, loves to hide its secrets in the thickest dust, and humans are relentless in their quest to uncover them. Yet, the dust poses challenges, particularly in determining dust grain sizes—a critical indicator of planet formation.
ALMA will continue to lead the charge in observing these early stages, alongside the Very Large Array. But future facilities like the Square Kilometer Array (SKAO) and the Next Generation VLA (ngVLA) will join the effort, observing these disks at longer wavelengths to overcome current limitations. "Observations at longer wavelengths, combined with more sensitive ALMA data, will be key to advancing our understanding of early disk and planet formation," the authors conclude.
What do you think? Does this research challenge your understanding of how planets form? Could these findings reshape our view of the cosmic nursery? Share your thoughts in the comments below!
More information: M. J. Maureira et al, FAUST. XXVIII. High-Resolution ALMA Observations of Class 0/I Disks: Structure, Optical Depths, and Temperatures, arXiv (2025). DOI: 10.48550/arxiv.2510.19635 (https://dx.doi.org/10.48550/arxiv.2510.19635)
Citation: Trying to find baby planets swaddled in dust (2025, November 4) retrieved 4 November 2025 from https://phys.org/news/2025-11-baby-planets-swaddled.html
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