Thermal Structure Determines Kinematics: Vertical Shear Instability in Stellar Irradiated Protoplanetary Disks

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Hauptverfasser: Zhang, Shangjia, Zhu, Zhaohuan, Jiang, Yan-Fei
Format: Preprint
Veröffentlicht: 2024
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author Zhang, Shangjia
Zhu, Zhaohuan
Jiang, Yan-Fei
author_facet Zhang, Shangjia
Zhu, Zhaohuan
Jiang, Yan-Fei
contents Turbulence is crucial for protoplanetary disk dynamics, and Vertical Shear Instability (VSI) is a promising mechanism in outer disk regions to generate turbulence. We use Athena++ radiation module to study VSI in full and transition disks, accounting for radiation transport and stellar irradiation. We find that the thermal structure and cooling timescale significantly influence VSI behavior. The inner rim location and radial optical depth affect disk kinematics. Compared with previous vertically-isothermal simulations, our full disk and transition disks with small cavities have a superheated atmosphere and cool midplane with long cooling timescales, which suppresses the corrugation mode and the associated meridional circulation. This temperature structure also produces a strong vertical shear at $\mathrm{τ_*}$ = 1, producing an outgoing flow layer at $τ_* < 1$ on top of an ingoing flow layer at $τ_* \sim 1$. The midplane becomes less turbulent, while the surface becomes more turbulent with effective $α$ reaching $\sim10^{-2}$ at $τ_* \lesssim$1. This large surface stress drives significant surface accretion, producing substructures. Using temperature and cooling time measured/estimated from radiation-hydro simulations, we demonstrate that less computationally-intensive simulations incorporating simple orbital cooling can almost reproduce radiation-hydro results. By generating synthetic images, we find that substructures are more pronounced in disks with larger cavities. The higher velocity dispersion at the gap edge could also slow particle settling. Both properties are consistent with recent Near-IR and ALMA observations. Our simulations predict that regions with significant temperature changes are accompanied by significant velocity changes, which can be tested by ALMA kinematics/chemistry observations.
format Preprint
id arxiv_https___arxiv_org_abs_2404_05608
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Thermal Structure Determines Kinematics: Vertical Shear Instability in Stellar Irradiated Protoplanetary Disks
Zhang, Shangjia
Zhu, Zhaohuan
Jiang, Yan-Fei
Earth and Planetary Astrophysics
Astrophysics of Galaxies
Solar and Stellar Astrophysics
Turbulence is crucial for protoplanetary disk dynamics, and Vertical Shear Instability (VSI) is a promising mechanism in outer disk regions to generate turbulence. We use Athena++ radiation module to study VSI in full and transition disks, accounting for radiation transport and stellar irradiation. We find that the thermal structure and cooling timescale significantly influence VSI behavior. The inner rim location and radial optical depth affect disk kinematics. Compared with previous vertically-isothermal simulations, our full disk and transition disks with small cavities have a superheated atmosphere and cool midplane with long cooling timescales, which suppresses the corrugation mode and the associated meridional circulation. This temperature structure also produces a strong vertical shear at $\mathrm{τ_*}$ = 1, producing an outgoing flow layer at $τ_* < 1$ on top of an ingoing flow layer at $τ_* \sim 1$. The midplane becomes less turbulent, while the surface becomes more turbulent with effective $α$ reaching $\sim10^{-2}$ at $τ_* \lesssim$1. This large surface stress drives significant surface accretion, producing substructures. Using temperature and cooling time measured/estimated from radiation-hydro simulations, we demonstrate that less computationally-intensive simulations incorporating simple orbital cooling can almost reproduce radiation-hydro results. By generating synthetic images, we find that substructures are more pronounced in disks with larger cavities. The higher velocity dispersion at the gap edge could also slow particle settling. Both properties are consistent with recent Near-IR and ALMA observations. Our simulations predict that regions with significant temperature changes are accompanied by significant velocity changes, which can be tested by ALMA kinematics/chemistry observations.
title Thermal Structure Determines Kinematics: Vertical Shear Instability in Stellar Irradiated Protoplanetary Disks
topic Earth and Planetary Astrophysics
Astrophysics of Galaxies
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2404.05608