Compilation of pebble mass flux vs. time evolutions. Solid lines show models developed in this study for various gap positions (see Sect. 3.1), which can be compared to mass fluxes required in pebble accretion simulations to form diverse inner planetary systems (dashed area, see M. Lambrechts et al. 2019) and the pebble mass flux inferred for the inner solar system using models capable of matching the NC/CC isotopic dichotomy (red dashed, see T. Lichtenberg et al. 2021). Symbols show ages and cold water masses of all 21 objects in our sample computed from JWST/MIRI line ratios (Table 1) in combination with Eq. 4 (see Appendix A), and the left and right y-axes are related through Eq. 3. Symbol color corresponds to inner gap position as obtained from high-spatial-resolution ALMA observations (see Sect. 2) and error-bars reflect uncertainties in measured line ratios. — astro-ph.EP
The influx of icy pebbles to the inner regions of protoplanetary disks constitutes a fundamental ingredient in most planet formation theories.
The observational determination of the magnitude of this pebble flux and its dependence on disk substructure (disk gaps as pebble traps) would be a significant step forward. In this work we analyze a sample of 21 T Tauri disks (with ages ≈0.5−2 Myr) using JWST/MIRI spectra homogeneously reduced with the JDISCS pipeline and high-angular-resolution ALMA continuum data.
We find that the 1500/6000 K water line flux ratio measured with JWST – a tracer of cold water vapor and pebble drift near the snowline – correlates with the radial location of the innermost dust gap in ALMA continuum observations (ranging from 8.7 to 69 au), confirming predictions from recent models that study connections between the inner and outer disk reservoirs.
We develop a population synthesis exploration of pebble drift in gapped disks and find a good match to the observed trend for early and relatively effective gaps, while scenarios where pebble drift happens quickly, gaps are very leaky, or where gaps form late are disfavored on a population level.
Inferred snowline pebble mass fluxes (ranging between 10−6 and 10−3 M⊕/yr depending on gap position) are comparable to fluxes used in pebble accretion studies and those proposed for the inner Solar System, while system-to-system variations suggest differences in the emerging planetary system architectures and water budgets.
Sebastiaan Krijt, Andrea Banzatti, Ke Zhang, Paola Pinilla, Till Kaeufer, Edwin A. Bergin, Colette Salyk, Klaus Pontoppidan, Geoffrey A. Blake, Feng Long, Jane Huang, María José Colmenares, Joe Williams, Adrien Houge, Mayank Narang, Miguel Vioque, Michiel Lambrechts, L. Ilsedore Cleeves, Karin Öberg, the JDISCS collaboration
Comments: Accepted for publication in ApJL, 15 pages, 6 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2508.10402 [astro-ph.EP] (or arXiv:2508.10402v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2508.10402
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Submission history
From: Sebastiaan Krijt
[v1] Thu, 14 Aug 2025 07:04:38 UTC (15,616 KB)
https://arxiv.org/abs/2508.10402
Astrobiology,