The study, led by Naman Bajaj of the University of Arizona and co-authored by SETI Institute scientist Uma Gorti, uses archival observations from JWST’s Mid-Infrared Instrument, or MIRI. The instrument is particularly valuable for studying warm molecular and atomic gas surrounding young stars because it can detect faint infrared emissions hidden from many earlier observatories. Instead of following one planetary system through millions of years—a task impossible within a human lifetime—the researchers assembled observations of systems at different ages. Together, the systems act like separate frames in a cosmic time-lapse movie, allowing scientists to reconstruct how winds evolve during the first few million years of planet formation.

The results, published in The Astronomical Journal, focus on two important tracers of escaping material: molecular hydrogen and ionized neon. Molecular hydrogen is the most abundant molecule in protoplanetary disks and can reveal broad, relatively cool winds flowing away from the disk. Ionized neon, by contrast, is produced in energetic environments and can identify hotter atomic gas, including fast jets and high-velocity outflows. Because the two signals arise under different physical conditions, comparing them allows astronomers to distinguish between several processes that remove gas from a young planetary system. The team detected extended emissions from molecular hydrogen and ionized neon in 66 of the 72 disks examined.

The observations show that the earliest stages of planetary-system development are dominated by energetic outflows linked to accretion. As material spirals inward through a disk and falls onto the young star, some of the gas can be redirected outward along magnetic field lines. These magnetically driven winds remove both mass and angular momentum, helping the remaining disk continue its inward flow. In many of the youngest systems, JWST revealed broad, conical winds containing molecular and atomic gas, as well as narrow, fast-moving jets traced by ionized neon. The researchers identified molecular hydrogen winds in 46 systems and neon jets in 40, showing that these structures are not rare exceptions but common features of early planetary evolution.

Magnetic fields provide the physical link between accretion and outflow. A young star and its surrounding disk rotate rapidly, twisting magnetic field lines and creating channels through which gas can be launched into space. Some material may be expelled from the surface of the disk, while other flows can emerge closer to the star and form collimated jets. These outflows are capable of carrying away substantial angular momentum, a crucial requirement for gas to move inward and feed the growing star. At the same time, they steadily reduce the reservoir available to future planets. The findings suggest that disk winds are not merely secondary effects of star formation; they are active forces that help determine whether planets have enough time to assemble.

The balance changes as a planetary system ages. Accretion onto the central star gradually declines, the strongest jets weaken, and the molecular component of the outflow becomes less prominent. As the disk thins, high-energy ultraviolet and X-ray radiation from the young star can penetrate deeper into the remaining gas. This radiation heats the gas and gives particles enough energy to escape the star’s gravity, a process known as photoevaporation. Unlike magnetically driven winds, which rely primarily on the disk’s magnetic structure and rotation, photoevaporative winds are powered by stellar radiation. The later-stage outflows observed by JWST are increasingly atomic, consistent with a transition from dense, magnetically controlled environments to more exposed and radiation-heated disks.

That transition has immediate consequences for planet formation. Protoplanetary disks typically contain far more gas than dust; during the early history of our own solar system, the disk surrounding the newborn Sun may have held roughly 100 times as much gas as dust. Dust grains collide and stick together, eventually building planetesimals and rocky planetary cores. If a core becomes sufficiently massive while hydrogen and helium remain abundant, it can rapidly capture a thick atmosphere and develop into a gas giant such as Jupiter or Saturn. But once disk dispersal accelerates, the supply of atmospheric gas can vanish. A planet that grows too slowly may remain a rocky or ice-rich world even if it formed in a region where a gas giant could otherwise have developed.

The new observations confirm predictions from earlier theoretical and observational work. In 2020, a team led by University of Arizona Lunar and Planetary Laboratory professor Ilaria Pascucci, who is also the second author of the current study and Bajaj’s advisor, predicted that molecular winds should be present in younger disks and could be dense enough to absorb or block X-ray radiation. At the time, astronomers could not directly observe molecular hydrogen in the relevant environments. JWST has now provided the needed sensitivity, revealing the predicted molecular outflows across a large sample and linking them to the later appearance of predominantly atomic winds. The study therefore connects models of disk evolution with direct infrared evidence from dozens of planetary systems.

The scale of the survey also changes the way scientists can think about disk dispersal. In earlier studies, a spectacular outflow from a single system could be interpreted in several ways because researchers did not know whether it represented a typical stage or an unusual event. The 72-system sample offers statistical context. Every system with a detected neon jet also showed evidence of a wind traced by molecular hydrogen or oxygen, indicating that jets and broader winds are closely related rather than independent phenomena. The observations support a picture in which planetary systems pass through overlapping phases: strong molecular and atomic outflows appear early, jets fade as accretion declines, and photoevaporative winds become increasingly influential as stellar radiation reaches the exposed disk.

The researchers’ next challenge is to measure how much gas each type of wind removes and determine precisely where the escaping material originates. The answer may reveal whether disk dispersal is controlled mainly by winds launched near the star, by evaporation from the outer disk, or by a combination of mechanisms that varies from system to system. Those measurements could also help explain the remarkable diversity of planets seen around other stars. Some systems may lose their gas rapidly and produce compact rocky worlds, while others may preserve their disks long enough to build massive gas giants. JWST’s survey shows that the end of a planet-forming disk is not a single event but an evolving contest between accretion, magnetic fields, stellar radiation, and gravity. In that contest, the moment when a young world gathers its atmosphere may be determined by how quickly its star blows the building materials away.

Subject of Research: The evolution and dispersal of protoplanetary disks through molecular winds, atomic winds, magnetically driven jets, and photoevaporation.

Article Title: JWST/MIRI Reveals the Evolution from Molecular to Atomic Disk Winds

News Publication Date: August 25, 2026

Web References: https://www.seti.org/people/uma-gorti/ ; https://doi.org/10.3847/1538-3881/ae9089

References: The Astronomical Journal, DOI: 10.3847/1538-3881/ae9089

Image Credits: ESA/NASA, the AVO project and Paolo Padovani

Keywords

James Webb Space Telescope, JWST, protoplanetary disks, planet formation, molecular hydrogen winds, atomic disk winds, photoevaporation, magnetically driven jets, young stars, gas giants, planetary systems, astronomy

Protoplanetary disks, swirling rings of gas and dust that encircle newborn stars, are environments where cosmic evolution unfolds at multiple scales. The journey from micron-sized dust particles to fully fledged planets is understood to involve a cascade of collisional agglomerations. Fine dust grains initially stick together through electrostatic forces, progressively growing to millimeter sizes. At the opposite end of the scale, planetesimals ranging from hundreds of meters to kilometers coalesce through gravitational collisions, eventually building terrestrial and giant planets. The intermediate stage, involving centimeter to hundred-meter-sized bodies, poses a formidable hurdle. In this size range, particles frequently rebound upon collision, fragment, or even evaporate due to close proximity to intense stellar radiation, stalling growth in a phenomenon commonly referred to as the “bouncing barrier.” This impasse has remained a significant puzzle for astrophysicists striving to unravel planetary genesis.

Theoretical explorations in recent decades suggested that hydrodynamical instabilities within the gas-dust mixture of the disk could serve as a catalyst to overcome this barrier. These instabilities, acting like fluid dynamical perturbations, can induce dust to coalesce into dense clusters, eventually collapsing into planetesimals. Among these, the shear-flow instability is particularly compelling as it arises at the interface between two fluid layers with differing velocities and densities — conditions intrinsic to protoplanetary disks. Prior to Capelo’s experiment, however, this mechanism was largely speculative, based on mathematical models and simulations without direct empirical validation, especially in the extraordinarily low-density, near-vacuum conditions of space.

Addressing this gap, the research team developed the TEMPus VoLA experiment, a uniquely designed instrument capable of probing dust-gas interactions in an exceptionally thin gas under microgravity. Employing the opportunities offered by parabolic flights that simulate near-weightless conditions for brief intervals of approximately 20 seconds, the experiment meticulously reproduces the delicate balance of forces present in space. The high-speed cameras integrated into the apparatus capture real-time dynamics of dust particles suspended in rarefied gas, isolating effects attributable solely to shear-flow without the confounding influence of Earth’s gravity.

Microgravity is essential because gravity on Earth causes sedimentation and convection in the gas-particle mixture, masking subtle instabilities that would occur in protoplanetary disks. By flying on specially adapted aircraft executing parabolic trajectories, the team recreated short bursts of near-zero gravity, allowing dust particles to be suspended in a stable manner akin to their natural state in space. Variations in gas density, dust concentration, and flow velocities were fine-tuned over multiple flights to identify precise conditions under which shear-flow instabilities manifest. This approach transcends theoretical predictions, providing tangible, visual confirmation of these phenomena.

Although the short duration of zero gravity in parabolic flights limits observation time, the experiment revealed distinct flow patterns signaling the early stages of instability formation. These characteristic structures reflect complex interactions between gas and dust particles, heralding transitions from laminar flow to turbulent states pivotal for density enhancement and clumping necessary for planetesimal creation. Such turbulence is thought to facilitate particle concentration by creating vortices and pressure traps, providing ideal niches for growth beyond the bouncing barrier. The findings thus substantiate long-held hypotheses that hydrodynamical effects, particularly shear-flow instabilities, are not mere theoretical curiosities but active agents sculpting early planetary architectures.

Recognizing the limitations of brief microgravity periods, Capelo’s team is advancing a more sophisticated version of the experiment designed for deployment aboard the International Space Station. The extended microgravity environment there would permit sustained observation of the instability’s full evolution into turbulence, unlocking insights inaccessible through Earth-bound methods or short-duration flights. This development heralds a new chapter in experimental astrophysics, enabling researchers to witness in situ processes that underpin planet formation with unprecedented clarity and precision.

Beyond enriching fundamental understanding, these experimental results carry significant implications for astrophysical modeling. Existing simulations of protoplanetary disks often struggle with resolution constraints, preventing them from accurately resolving the scale at which these instabilities operate. Data derived from the TEMPus VoLA experiment can be integrated to enhance physical models, refining inputs relating to gas viscosity, dust-gas coupling, and turbulence initiation. Enhanced models will improve predictions about planetesimal formation rates, disk evolution timelines, and hence the diversity of planetary systems emerging throughout the galaxy.

The corroboration of shear-flow instability under realistic protoplanetary conditions also sheds light on the origins of our own Solar System. While comets and asteroids serve as fossil records of early Solar System materials, they cannot directly reveal the intricate dynamical processes that governed their formation. Bridging this observational gap through laboratory and microgravity experiments adds a crucial dimension to comparative planetary science. Understanding how dust and gas behavior fostered planetesimals billions of years ago deepens appreciation of the material and energetic pathways culminating in Earth’s formation, and by extension, the conditions enabling life.

Realizing this ambitious research initiative necessitated a fusion of multidisciplinary expertise across Swiss academic institutions. The University of Bern spearheaded instrument development, leveraging technical precision in vacuum and optical engineering. The University of Zurich contributed crucial theoretical frameworks in planet formation, while ETH Zurich’s strengths in small body observation informed experimental parameters. Additionally, the UZH Space Hub, ESA/PRODEX programs, and the aerospace company Novespace brought essential experience in orchestrating and executing complex parabolic flight campaigns. This synergy exemplifies how collaborative networks catalyze breakthroughs unattainable by isolated efforts.

This Swiss-led breakthrough continues a proud legacy of Bernese contributions to space science, tracing back to 1969 when Prof. Dr. Johannes Geiss and his team at the University of Bern crafted the Solar Wind Composition experiment, which was deployed on the Moon by astronaut Buzz Aldrin. Since then, Bernese scientists have remained at the forefront of space missions with ESA, NASA, and JAXA, participating in both instrumentation and data analysis. The University of Bern now co-manages the CHEOPS mission for ESA and leads cutting-edge planetary formation modeling, further cementing its status among global leaders in space research.

To capitalize on these achievements, the University of Bern established the Center for Space and Habitability, a dedicated competence center focused on interdisciplinary exploration of planetary environments and habitability conditions. Furthermore, the integration within the National Center of Competence in Research (NCCR) PlanetS fosters cohesive national efforts to unravel planetary system formation. This institutional framework amplifies the impact of experimental and theoretical ventures such as TEMPus VoLA, shaping the frontiers of astrophysical knowledge.

As the TEMPus VoLA experiment paves the way for observing shear-flow instabilities under authentic cosmic conditions, scientists edge ever closer to unraveling the full narrative of planet formation. These results not only dismantle previous conceptual barriers but also open new horizons for exploring planetary origins both within our Solar System and beyond. The fusion of innovative experimentation, rigorous theory, and high-fidelity simulation propels this field into a dynamic era where cosmic origins are no longer confined to the realm of speculation but are illuminated through empirical evidence.

—

Subject of Research: Not applicable

Article Title: Experimental evidence for granular shear-flow instability in the Epstein regime

News Publication Date: 17-Mar-2026

Web References:
DOI link

Image Credits: Courtesy of Holly Capelo

Keywords

planet formation, protoplanetary disks, shear-flow instability, microgravity experiments, dust aggregation, planetesimals, hydrodynamical instabilities, parabolic flights, TEMPus VoLA, astrophysical fluid dynamics, turbulence, cosmic origins

In an extensive statistical analysis of 123 hot Jupiters orbiting single Sun-like stars, the research team uncovered a striking pattern in the frequency of these planets as a function of stellar age. Instead of a smooth and gradual decline over billions of years, the data reveals an abrupt change in the slope of this age-frequency relationship at roughly two billion years. This inflection suggests the existence of two distinct subpopulations of hot Jupiters—one forming early in a star system’s life, and another emerging significantly later. Such a dual-population model challenges simplified narratives that view hot Jupiter formation through a singular temporal lens, instead advocating for a nuanced, multichannel process operating on vastly different timescales.

The first population, representing the majority of hot Jupiters, appears to originate within a few hundred million years following star formation. These early hot Jupiters likely arise through mechanisms such as in situ formation, type II disk migration, planet–planet scattering, or Kozai–Lidov interactions driven by stellar companions. Each of these processes facilitates rapid inward movement of massive gaseous planets formed farther out or, in some cases, allows them to coalesce right where we observe them today. The swift formation and migration within this early timeframe explains the presence of mature hot Jupiters orbiting relatively young stars observed in various exoplanet surveys.

Conversely, a significant subset—approximately 38%, with uncertainties stretching from 24% up to 54%—forms much later, over a timescale extending to several billion years. This delayed population hints at the role of secular chaotic migration, a dynamical process occurring well after the dissipation of the protoplanetary disk. In secular chaos, gravitational interactions among multiple planets in an initially stable system lead to orbital perturbations and gradual eccentricity build-up. Eventually, one planet’s orbit shrinks close enough to the host star to become a hot Jupiter. This slow, chaotic evolution provides a natural explanation for the late arrival of these exoplanets.

To probe the dynamical evolution underpinning these observations, Chen and colleagues employed an advanced model of tidal dissipation. Tidal interactions between close-in planets and their host stars lead to orbital decay and eventual engulfment or stabilization. The efficiency of energy dissipation inside the star, often encapsulated by the dimensionless tidal quality factor ({Q}{}^{{\prime}}), remains one of the most uncertain — yet critical — parameters in modeling planet-star tidal evolution. By calibrating their population model against the observed age distribution and orbital parameters of hot Jupiters, the team constrained (\log {Q}{}^{{\prime}} \approx 5.7^{+0.4}_{-0.3}) for Sun-like stars.

This derived tidal quality factor estimate implies moderately efficient tidal dissipation, sufficient to drive observable orbital decay in a subset of hot Jupiters within their lifetimes. Importantly, this value is consistent with recent theoretical predictions and provides a benchmark for future research aiming to clarify the complex interplay between stellar structure, rotation, and tidal friction. The model’s ability to reproduce the observed frequency and age distribution of hot Jupiters undergoing decay marks a significant advance in understanding their long-term orbital stability.

The dual-population framework also sheds light on the intriguing obliquity distribution among hot Jupiters—the tilt of a planet’s orbital plane relative to the spin axis of its host star. Early-forming hot Jupiters commonly display low obliquities, consistent with smooth and aligned migration mechanisms such as disk-driven migration. On the other hand, the ‘late-arriving’ hot Jupiters tend to exhibit a broader range of obliquities, many with significant misalignments, mirroring the chaotic and stochastic nature of secular interactions. This correlation validates the proposed formation timescales and origins, linking system dynamics to observed orbital geometries.

These insights collectively forge a unifying framework that reconciles hot Jupiter demographics, formation theories, and their tidal evolution. By framing the observed exoplanet population as the composite outcome of multiple migration channels, each operating over distinct temporal windows, the study captures the complexity of planetary system evolution—a complexity that simpler, monolithic models fail to accommodate. The findings also emphasize the critical role of long-term dynamical interactions beyond the traditional disk migration epoch, reaffirming that planetary systems remain highly dynamic over billions of years.

Beyond advancing exoplanetary science, these revelations have profound implications for efforts to characterize habitable worlds and planetary system architectures. Understanding the mechanisms that drive hot Jupiters inward—often destabilizing the orbits of smaller, terrestrial planets—helps refine estimates of planetary habitability zones and informs searches for Earth-like exoplanets in dynamically quiescent environments. Moreover, the improved constraints on stellar tidal dissipation enrich models of stellar rotational evolution, angular momentum exchange, and magnetic braking.

Looking forward, the study by Chen et al. guides observational strategies aimed at identifying and characterizing late-forming hot Jupiters. Upcoming missions with precision astrometry and radial velocity capabilities can test the predicted fractions and orbital decay signatures. Meanwhile, long-baseline photometry and transit timing variations offer promising avenues to detect subtle changes in orbital periods indicative of tidal interactions. Further, high-resolution spectroscopy probing stellar obliquities will continue to elucidate the links between dynamical histories and planetary orbits.

In the broader context of astrophysics, this work exemplifies the power of combining statistical planet populations with detailed dynamical modeling to unravel complex evolutionary scenarios. The methodology—integrating stellar age estimates, comprehensive planet catalogs, and sophisticated tidal physics—paves the way for similar investigations across diverse exoplanet types and stellar hosts. Such approaches promise to deepen our grasp of planetary system formation in the galaxy, illuminating the myriad pathways through which diverse planetary architectures emerge.

The discovery that hot Jupiters are not a monolithic population but instead comprise distinct cohorts formed under disparate conditions and timescales challenges long-standing paradigms. It reinforces the notion that the fates of planets are intricately linked to the intertwined processes of formation, migration, and tidal evolution, each leaving signatures decipherable only through meticulous analysis. This study stands as a milestone in exoplanet science, revealing a richer narrative of the hot Jupiter phenomenon and providing a robust scaffold for future theoretical and observational endeavors.

As we continue to explore the extensive diversity of exoplanets, the lesson of hot Jupiters reminds us that planetary systems are sculpted by a web of processes evolving over cosmic time. The interplay between gravitational dynamics, disk physics, and stellar interiors creates a cinematic saga—one where planets can form early and settle quickly into their orbits, or wander chaotically through gravitational interactions only to become hot Jupiters billions of years later. This dual-picture not only narrates planetary origins but also connects us more intimately to the vast, evolving cosmos of which the Sun and its retinue of planets are but one compelling chapter.

Subject of Research: The origin and tidal evolution of hot Jupiters, with a focus on the age-frequency relationship and tidal dissipation in Sun-like stars.

Article Title: The origin and tidal evolution of hot Jupiters constrained by a broken age–frequency relation.

Article References:
Chen, DC., Xie, JW., Zhou, JL. et al. The origin and tidal evolution of hot Jupiters constrained by a broken age–frequency relation. Nat Astron (2025). https://doi.org/10.1038/s41550-025-02693-6

Image Credits: AI Generated

Historically viewed only as ephemeral constructs lasting a mere 10 million years, these planet-forming disks, with their intricate composition of gas and dust, serve as vital incubators for planetary systems. New findings have challenged this conventional timeline, revealing that under certain conditions, particularly in low-mass stellar environments, these disks can persist for significantly longer durations than previously assumed. Such discoveries open new vistas in the understanding of planet formation, suggesting that the universe may be more nurturing to planetary life than previously thought.

Feng Long, a prominent researcher and lead author of the ground-breaking study published in the Astrophysical Journal Letters, remarked on these findings, asserting that protoplanetary disks function similarly to "baby pictures" of planetary systems. By analyzing the protoplanetary disk surrounding a star designated as WISE J044634.16–262756.1B, or more simply known as J0446B, the research team has indicated that the disk boasts an extraordinary age of approximately 30 million years. This striking longevity, almost three times longer than what has been conventionally recorded for disks around stars, prompts a reevaluation of how we perceive the lifecycle of these cosmic structures.

The pioneering work utilized NASA’s James Webb Space Telescope to conduct an unprecedented detailed chemical analysis of this long-lived disk, resulting in remarkable revelations regarding its composition. This investigation uncovered gases such as hydrogen and neon within the disk, conclusively ruling out the classification of J0446B’s disk as merely a debris disk—an older type of disk less conducive to the formation of new planets. Instead, the presence of primordial gases indicates a dynamic, ongoing process likely contributing to the formation of planets around this low-mass star.

Low-mass stars, defined as those with masses one-tenth that of our Sun or less, dominate the cosmos by number, with a prevalence that surpasses their more massive counterparts. This raises pertinent questions about how these stars develop and maintain their protoplanetary disks over extended time frames. Long’s observations note that as stellar masses decrease, the energy output also diminishes, resulting in a gentler environment where the gas and dust elements of the disk may persist longer before being expelled by stellar winds.

The implications of these findings extend beyond mere curiosity, reaching into the realm of astrobiology and planetary habitability. For example, the TRAPPIST-1 system, located 40 light-years from Earth and renowned for its seven Earth-sized planets, captures the interest of researchers due to its potential for harboring life. Long and her colleagues suggest that the long-lasting nature of gas-rich disks around stars like J0446B could mirror conditions in such planetary systems, offering them a more extended period in which to develop life-sustaining properties.

Ilaria Pascucci, a co-author and influential figure in planetary science, highlighted the significance of the long-lived disks in relation to orbit migration. For planets to achieve the distinct orbital arrangements observed in the TRAPPIST-1 system, migration through the surrounding gas must occur—a process that inherently relies on the presence of the disk’s gaseous material over extended time spans. Therefore, the continued identification of gas-rich, long-lived disks offers tantalizing possibilities for understanding how diverse planetary systems may evolve through time.

Furthermore, the study’s findings could reshape theoretical models surrounding star and planet development. The traditional perspectives on how quickly high-mass star systems evolve—often resulting in rapid disk dissipation—stand in contrast to the mistaken notion that all star types share similar behaviors in disk longevity. By establishing this nuanced understanding, researchers can begin to piece together the mechanisms that drive the evolution of low-mass stars, potentially leading to groundbreaking discoveries regarding planetary formation across the galaxy.

Overall, the dedicated efforts of the University of Arizona team underscore the importance of ongoing observations through advanced telescopes, fueling the quest for knowledge about our universe. As researchers continue to probe the rich, diverse territory of stellar and planetary development, notions of what constitutes a habitable zone or a potential nursery for life could be vastly redefined. Thus, as we gather more insights into the endlessly fascinating phenomena surrounding protoplanetary disks, the prospect of discovering unique planetary systems—and perhaps even life itself—remains tantalizingly close on the horizon.

As our understanding of these celestial structures evolves, we are reminded of the infinite possibilities that lay within the cosmos. The survival of planet-forming disks beyond their expected lifespan highlights the complexity of star formation and the potential for life in environments previously deemed unviable. This new knowledge beckons scientists and enthusiasts alike to further explore the endless wonders of the universe, forever expanding our cosmic photo album, one discovery at a time.

Through these groundbreaking revelations and insights, the study exemplifies how modern astronomy can illuminate the intricate pathways through which stars and planets come into existence and potentially harbor life. The research not only enriches our understanding of celestial mechanics but also intertwines with our hopes and questions regarding the fabric of life beyond our home planet. As we gaze into the cosmos, we are perpetually reminded of our connection to the stars and the timeless quest to unravel the mysteries they hold.

Subject of Research: Observational study of long-lived planet-forming disks around low-mass stars.
Article Title: The First JWST View of a 30-Myr-old Protoplanetary Disk Reveals a Late-stage Carbon-rich Phase
News Publication Date: 6-Jan-2025
Web References: http://dx.doi.org/10.3847/2041-8213/ad99d2
References: Not applicable
Image Credits: Credit: NASA/CXC/M. Weiss

Keywords

Stellar formation, protoplanetary disks, planetary evolution, low-mass stars, TRAPPIST-1 system, James Webb Space Telescope, cosmic chemistry, astrophysics, observational astronomy.