Convective Overstability in Radially Global Protoplanetary Disks. II. Impact on Planetesimal Formation

The convective overstability (COS) is a hydrodynamic instability occurring in protoplanetary disk (PPD) regions with an adverse radial entropy gradient. It is a potential driver of turbulence and may influence planetesimal formation. In this second paper of our series, we study the effects of the CO...

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Main Authors: Marius Lehmann, Min-Kai Lin
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adbf06
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author Marius Lehmann
Min-Kai Lin
author_facet Marius Lehmann
Min-Kai Lin
author_sort Marius Lehmann
collection DOAJ
description The convective overstability (COS) is a hydrodynamic instability occurring in protoplanetary disk (PPD) regions with an adverse radial entropy gradient. It is a potential driver of turbulence and may influence planetesimal formation. In this second paper of our series, we study the effects of the COS on dust dynamics in radially global PPD simulations, focusing on the midplane region, where vertical gravity on the dust is included. Axisymmetric 2D simulations show susceptibility to both the COS and the vertically shearing streaming instability. For a Stokes number τ  = 0.1, strong dust clumping occurs only for highly supersolar initial metallicities Z  ≳ 0.05. In 3D nonaxisymmetric simulations, the COS generates large-scale, long-lived vortices that have the potential to efficiently concentrate dust, with dust accumulation strengthening as τ increases. For τ  = 0.01, no strong clumping occurs even at metallicities as high as Z = 0.1, and vortices remain robust and long-lived. At τ  ≈ 0.04, strong dust clumping is observed for solar metallicity ( Z = 0.01) and higher. For τ  = 0.1, clumping occurs even at strongly subsolar metallicities ( Z  ≳ 0.004), peaking at Z  ∼ 0.01–0.03, including solar values. Under these conditions, vortices weaken significantly. At higher metallicities ( Z  ≳ 0.04) with τ  = 0.1, large-scale vortex formation is suppressed, leading to nearly axisymmetric dust rings, which can still undergo clumping via the classical streaming instability.
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spelling doaj-art-a9e1eb6d5f934d1893dfd3fa7c9f2c412025-08-20T02:12:41ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01983213510.3847/1538-4357/adbf06Convective Overstability in Radially Global Protoplanetary Disks. II. Impact on Planetesimal FormationMarius Lehmann0https://orcid.org/0000-0002-0496-3539Min-Kai Lin1https://orcid.org/0000-0002-8597-4386Institute of Astronomy and Astrophysics , Academia Sinica, Taipei 10617, Taiwan ; mlehmann@asiaa.sinica.edu.twInstitute of Astronomy and Astrophysics , Academia Sinica, Taipei 10617, Taiwan ; mlehmann@asiaa.sinica.edu.tw; Physics Division, National Center for Theoretical Sciences , Taipei 10617, TaiwanThe convective overstability (COS) is a hydrodynamic instability occurring in protoplanetary disk (PPD) regions with an adverse radial entropy gradient. It is a potential driver of turbulence and may influence planetesimal formation. In this second paper of our series, we study the effects of the COS on dust dynamics in radially global PPD simulations, focusing on the midplane region, where vertical gravity on the dust is included. Axisymmetric 2D simulations show susceptibility to both the COS and the vertically shearing streaming instability. For a Stokes number τ  = 0.1, strong dust clumping occurs only for highly supersolar initial metallicities Z  ≳ 0.05. In 3D nonaxisymmetric simulations, the COS generates large-scale, long-lived vortices that have the potential to efficiently concentrate dust, with dust accumulation strengthening as τ increases. For τ  = 0.01, no strong clumping occurs even at metallicities as high as Z = 0.1, and vortices remain robust and long-lived. At τ  ≈ 0.04, strong dust clumping is observed for solar metallicity ( Z = 0.01) and higher. For τ  = 0.1, clumping occurs even at strongly subsolar metallicities ( Z  ≳ 0.004), peaking at Z  ∼ 0.01–0.03, including solar values. Under these conditions, vortices weaken significantly. At higher metallicities ( Z  ≳ 0.04) with τ  = 0.1, large-scale vortex formation is suppressed, leading to nearly axisymmetric dust rings, which can still undergo clumping via the classical streaming instability.https://doi.org/10.3847/1538-4357/adbf06Astrophysical fluid dynamicsPlanet formationMagnetohydrodynamical simulationsProtoplanetary disksPlanetesimals
spellingShingle Marius Lehmann
Min-Kai Lin
Convective Overstability in Radially Global Protoplanetary Disks. II. Impact on Planetesimal Formation
The Astrophysical Journal
Astrophysical fluid dynamics
Planet formation
Magnetohydrodynamical simulations
Protoplanetary disks
Planetesimals
title Convective Overstability in Radially Global Protoplanetary Disks. II. Impact on Planetesimal Formation
title_full Convective Overstability in Radially Global Protoplanetary Disks. II. Impact on Planetesimal Formation
title_fullStr Convective Overstability in Radially Global Protoplanetary Disks. II. Impact on Planetesimal Formation
title_full_unstemmed Convective Overstability in Radially Global Protoplanetary Disks. II. Impact on Planetesimal Formation
title_short Convective Overstability in Radially Global Protoplanetary Disks. II. Impact on Planetesimal Formation
title_sort convective overstability in radially global protoplanetary disks ii impact on planetesimal formation
topic Astrophysical fluid dynamics
Planet formation
Magnetohydrodynamical simulations
Protoplanetary disks
Planetesimals
url https://doi.org/10.3847/1538-4357/adbf06
work_keys_str_mv AT mariuslehmann convectiveoverstabilityinradiallyglobalprotoplanetarydisksiiimpactonplanetesimalformation
AT minkailin convectiveoverstabilityinradiallyglobalprotoplanetarydisksiiimpactonplanetesimalformation