Accretion across scales: streamers, surface-layer transport, and rapid replenishment in young protoplanetary discs
Abstract
Protoplanetary discs evolve around newly-formed stars through an interplay of infall from surrounding turbulent cloud material, accretion towards the young star, and outflow driven mass-loss. It has been challenging to determine if discs are fed predominantly through infall along the disc midplane, or along the poles, and if accretion occurs in a steady or burst-like fashion. Here, we present a suite of 3D ideal magnetohydrodynamical simulations of protoplanetary disc formation and evolution in a dynamic, large-scale molecular cloud environment using the adaptive mesh refinement framework DISPATCH. We focus on nine stellar systems, where we resolve discs down to a scale of 0.8 au. Across the sample, stellar accretion proceeds at rates of ∼10−5 M⊙ yr−1 over 105 yr, with significant variability. Discs grow to 100 au scales and remain gravitationally stable in time, with disc-to-star mass ratios below 10 %. Transient high-density streamers, with 10 kyr infall times, can drive anisotropic mass delivery at rates comparable to the background accretion flow. Their interaction with discs typically results in a temporary reduction of the disc size by half, and disc mass by 40 %. During later quiescent disc evolution stages (t≳50 kyr), accretion predominantly occurs through the midplane and disc surface layers. This is associated with the development of a toroidal magnetic field morphology, which includes field reversals across both disc surfaces. In this way, the full disc mass reservoir is replenished on 10 kyr-timescales. These findings support that the outer parts of very young discs, when well-ionised and close to the ideal MHD regime, are not yet conducive to planet formation, due to high replenishment rates, strong turbulence, and disruptive streamer infall events.
Versions
Related
- Dynamical Impacts of Accretion Streamers on Protoplanetary Disks
- Dynamical Impacts of Accretion Streamers on Protoplanetary Disks
- From streamers to stars: Overcoming mass loss in protoplanetary disks
- From streamers to stars: Overcoming mass loss in protoplanetary disks
- Radiation Hydrodynamics of Self-gravitating Protoplanetary Disks II. Accretion, Migration, Spin, and Internal Structure of GI Fragments
BibTeX
@misc{holm2026accretion,
title = {{Accretion across scales: streamers, surface-layer transport, and rapid replenishment in young protoplanetary discs}},
author = {Christian Granzow Holm and Michiel Lambrechts and Michael Kuffmeier and Anders Johansen and Troels Haugbølle and Åke Nordlund},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.02204},
eprint = {2608.02204},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.02204},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Accretion across scales: streamers, surface-layer transport, and rapid replenishment in young protoplanetary discs
AU - Christian Granzow Holm
AU - Michiel Lambrechts
AU - Michael Kuffmeier
AU - Anders Johansen
AU - Troels Haugbølle
AU - Åke Nordlund
PY - 2026
DA - 2026/08/03
PB - arXiv
DO - 10.48550/arxiv.2608.02204
UR - https://arxiv.org/abs/2608.02204
AB - Protoplanetary discs evolve around newly-formed stars through an interplay of infall from surrounding turbulent cloud material, accretion towards the young star, and outflow driven mass-loss. It has been challenging to determine if discs are fed predominantly through infall along the disc midplane, or along the poles, and if accretion occurs in a steady or burst-like fashion. Here, we present a suite of 3D ideal magnetohydrodynamical simulations of protoplanetary disc formation and evolution in a dynamic, large-scale molecular cloud environment using the adaptive mesh refinement framework DISPATCH. We focus on nine stellar systems, where we resolve discs down to a scale of 0.8 au. Across the sample, stellar accretion proceeds at rates of ∼10^−5 M_⊙ yr^−1 over 10^5 yr, with significant variability. Discs grow to 100 au scales and remain gravitationally stable in time, with disc-to-star mass ratios below 10 %. Transient high-density streamers, with 10 kyr infall times, can drive anisotropic mass delivery at rates comparable to the background accretion flow. Their interaction with discs typically results in a temporary reduction of the disc size by half, and disc mass by 40 %. During later quiescent disc evolution stages (t≳50 kyr), accretion predominantly occurs through the midplane and disc surface layers. This is associated with the development of a toroidal magnetic field morphology, which includes field reversals across both disc surfaces. In this way, the full disc mass reservoir is replenished on 10 kyr-timescales. These findings support that the outer parts of very young discs, when well-ionised and close to the ideal MHD regime, are not yet conducive to planet formation, due to high replenishment rates, strong turbulence, and disruptive streamer infall events.
ER -