Protoplanetary Disks and Filamentary Accretion in Stellar Nurseries
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New multi-wavelength observations reveal that planet-forming (protoplanetary) disks are chemically complex, longer-lived than previously believed, and dynamically linked to large-scale filamentary gas flows that fuel stellar nurseries. This publication synthesizes JWST and ALMA discoveries with new cloud-scale surveys to present an updated model of disk evolution within the Stellar Nursery Observation Initiative (SNOI).
Observations: JWST + ALMA + Large-Scale Gas Surveys
SNOI combines JWST infrared spectroscopy, ALMA sub-millimeter imaging, and molecular-cloud kinematic surveys to create a complete multi-scale view of star and planet formation. JWST uncovers inner-disk composition, ALMA resolves outer-disk structures, and cloud-scale maps reveal the filamentary networks feeding these systems.
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JWST: Inner-Disk Structure and Chemistry
JWST MIRI/NIRSpec observations reveal warm molecules such as H2O, CO, CO2, and complex organics in the inner astronomical unit of disks. These signatures refine predictions for Earth-like planet composition and point to a diverse range of volatile environments.
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ALMA: Outer-Disk Gas, Rings, and Kinematics
ALMA surveys resolve rings, gaps, spirals, and gas flows in the outer tens to hundreds of AU. These structures provide evidence for early planet formation and the dynamic redistribution of dust and gas across the disk.
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Filamentary Networks Feeding Forming Stars
Large molecular-line surveys reveal that dense interstellar filaments act as cosmic pipelines. They transport material into gravitational hubs and protostellar cores, sustaining long-term accretion and significantly extending disk lifetimes.
Analysis I: Disk Lifetimes, Dust Evolution, and Chemistry
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Evidence for Extended Disk Lifetimes
A growing number of observed disks persist for 5–10 million years, longer than classical estimates. This persistence is linked to environmental shielding, low UV radiation, and continuous mass replenishment from envelopes and filaments.
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Chemical Gradients and Planet-Building Materials
JWST detections of CO2-rich and water-poor zones highlight strong radial chemical differences. These gradients influence the type of atmospheres and volatile inventories planets will inherit during formation.
Analysis II: Filamentary Accretion — From Cloud to Disk
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Hierarchical Feeding: Filament → Hub → Core → Disk
Observations show gas streaming along filaments into dense hubs. These hubs fragment into protostellar cores, where additional small-scale flows and streamers deliver mass directly onto circumstellar disks, boosting accretion rates and altering disk angular momentum.
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Gas Transfer Signatures in Protostellar Disks
Velocity-bridge features and inverse P-Cygni profiles from molecules such as HCO+ and N2H+ provide unambiguous evidence that disks are still being fed by surrounding gas reservoirs, reinforcing the concept of externally sustained disk growth.
Discussion: Implications for Planet Formation
The coupling between disk chemistry, filamentary accretion, and large-scale cloud structure implies that planet formation is not an isolated process. Instead, it is shaped by continuous environmental interactions, affecting planet migration, atmospheric composition, and long-term system architecture.
Conclusion: A Multi-Scale Path to Predictive Planet Formation Models
SNOI’s multi-wavelength approach shows that to accurately predict the planets formed within a system, we must connect disk physics to the larger molecular-cloud environment. Upcoming JWST and ALMA programs, coordinated with filament-mapping surveys, will further refine the next generation of planet formation models.
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