From streamers to stars: Overcoming mass loss in protoplanetary disks

@misc{ooyama2026from,
  title = {{From streamers to stars: Overcoming mass loss in protoplanetary disks}},
  author = {W. Ooyama and R. Nakatani and T. Hosokawa and H. Mitani},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2605.26764},
  eprint = {2605.26764},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2605.26764},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - From streamers to stars: Overcoming mass loss in protoplanetary disks
AU  - W. Ooyama
AU  - R. Nakatani
AU  - T. Hosokawa
AU  - H. Mitani
PY  - 2026
DA  - 2026/10/13
PB  - arXiv
DO  - 10.48550/arxiv.2605.26764
UR  - https://arxiv.org/abs/2605.26764
AB  - Recent high-resolution observations have revealed filamentary accretion flows (``streamers'') in protoplanetary disks older than 1 Myr, suggesting that late-stage interstellar gas infall (late infall) may affect disk evolution and stellar accretion. In Lupus, observations report a positive correlation between ambient gas density and stellar accretion rate. However, it remains unclear whether infall can truly boost stellar accretion, because incoming gas may instead be lost through photoevaporation or magnetically driven disk winds, or remain trapped in the outer disk. We perform one-dimensional long-term (∼1--10 Myr) disk evolution simulations. We first treat late infall as a mass source and then include the effective torque arising from the angular-momentum difference between the infalling gas and Keplerian disk gas. We find that even if substantial gas reaches the outer disk (∼ 10^2 au), much of it is eventually lost through photoevaporation. Sustained stellar accretion therefore requires efficient inward gas delivery by mechanisms that locally remove angular momentum. Without an effective infall torque, strong viscosity can provide this transport, but it also drives outward angular-momentum transport and excessive disk spreading, inconsistent with the compact disk sizes observed in Lupus. In contrast, MHD disk winds can remove angular momentum without significantly expanding the disk, allowing late infall to sustain stellar accretion while keeping disks compact. Thus, if the Lupus accretion--density correlation is caused by late infall without an effective infall torque, efficient angular-momentum removal by MHD disk winds is required. By contrast, when the effective torque is included, the angular-momentum mismatch itself can promote inward gas transport and enhance stellar accretion, even without strong MHD disk winds.
ER  -