16:30 〜 16:45
[PPS07-17] Dust ring and gap formation by gas flow induced by low-mass planets embedded in a protoplanetary disk
キーワード：原始惑星系円盤、惑星形成
Recent high-spatial resolution observations have revealed dust substructures such as rings and gaps in protoplanetary disks (e.g., Andrews et al. 2018). Disk-planet interaction is one of the possible origins of the observed dust substructures in disks. A giant planet forms a gas gap in a disk. The young protoplanetary disks contain abundant millimeter-centimeter (mm–cm)-sized particles. The solid materials can be trapped at the edge of the gas gap, the so-called dust filtration mechanism, and then the dust substructures form.
On the assumption that a gap-opening planet forms dust substructures, one would expect that the spatial distribution of dust substructures is correlated with that of gas. However, recent studies show that the correlation between the spatial distribution of gas and dust substructures in a disk is ambiguous (e.g., Zhang et al. 2021; Jiang et al. 2021).
In this study, we focus on the potential of gas flow induced by low-mass, non-gap-opening planets to sculpt dust substructures in protoplanetary disks. Recent hydrodynamical simulations have revealed that a low-mass planet embedded in a disk induces gas flow with a complex three-dimensional (3D) structure (e.g., Ormel et al. 2015; Fung et al. 2015). The planet-induced gas flow has the potential to affect the radial distribution of dust in a disk. The key point is the outflow of the gas, which occurs in the radial direction of the disk. The outflow of the gas deflects significantly the trajectories of small particles, even when the planet is small (~1M⊕; Kuwahara & Kurokawa 2020a,b).
To investigate the influence of the planet-induced gas flow on the radial distribution of dust in a disk, we first performed 3D hydrodynamical simulations. We then numerically integrated the equation of motion for dust particles in 3D using hydrodynamical simulation data and obtained the spatial distribution of dust particles. Finally, we compute the dust surface density by solving an onedimensional (1D) advection-diffusion equation using orbital calculation data.
We found that the outflow of the gas perturbed significantly the drift velocity of dust partilces. The dust is accumulated (dust ring) outside the planetary orbit and depleted (dust gap) around the planetary orbit due to the planet-induced gas flow. We found that the dust ring and gap are likely to form when the Stokes number, St=tstopΩK, is small, where tstop is the stopping time of particle and ΩK is the Keplerian orbital frequency. This is because the smaller dust particles are more sensitive to the gas flow.
The gas flow induced by low-mass planets can be considered as one of the possible origins of the observed dust substructuers in disks. The characteristics of the dust ring and gap formed by the planet-induced gas flow are summarized as follows:
1. The planet-induced gas flow forms the ring and (or) gap in the distribution of aerodynamically small dust grains, St≦10-3.
2. The gas flow induced by a low-mass embedded planet can generate the dust ring and (or) gap in the vicinity of the planet location without creating gas gap or pressure bump.
Based on our results, we discuss the implications for the existence of the distant low-mass planets.
References:
Andrews, S. M., Huang, J., Pérez, L. M., et al. 2018, The Astrophysical Journal Letters, 869, L41
Zhang, K., Booth, A. S., Law, C. J., et al. 2021, The Astrophysical Journal Supplement Series, 257, 5
Jiang, H., Zhu, W., & Ormel, C. W. 2021, arXiv preprint arXiv:2112.13859
Ormel, C. W., Shi, J.-M., & Kuiper, R. 2015, MNRAS, 447, 3512
Fung, J., Artymowicz, P., & Wu, Y. 2015, ApJ, 811, 101
Kuwahara, A. & Kurokawa, H. 2020a, A&A, 633, A81
Kuwahara, A. & Kurokawa, H. 2020b, A&A, 643, A21
On the assumption that a gap-opening planet forms dust substructures, one would expect that the spatial distribution of dust substructures is correlated with that of gas. However, recent studies show that the correlation between the spatial distribution of gas and dust substructures in a disk is ambiguous (e.g., Zhang et al. 2021; Jiang et al. 2021).
In this study, we focus on the potential of gas flow induced by low-mass, non-gap-opening planets to sculpt dust substructures in protoplanetary disks. Recent hydrodynamical simulations have revealed that a low-mass planet embedded in a disk induces gas flow with a complex three-dimensional (3D) structure (e.g., Ormel et al. 2015; Fung et al. 2015). The planet-induced gas flow has the potential to affect the radial distribution of dust in a disk. The key point is the outflow of the gas, which occurs in the radial direction of the disk. The outflow of the gas deflects significantly the trajectories of small particles, even when the planet is small (~1M⊕; Kuwahara & Kurokawa 2020a,b).
To investigate the influence of the planet-induced gas flow on the radial distribution of dust in a disk, we first performed 3D hydrodynamical simulations. We then numerically integrated the equation of motion for dust particles in 3D using hydrodynamical simulation data and obtained the spatial distribution of dust particles. Finally, we compute the dust surface density by solving an onedimensional (1D) advection-diffusion equation using orbital calculation data.
We found that the outflow of the gas perturbed significantly the drift velocity of dust partilces. The dust is accumulated (dust ring) outside the planetary orbit and depleted (dust gap) around the planetary orbit due to the planet-induced gas flow. We found that the dust ring and gap are likely to form when the Stokes number, St=tstopΩK, is small, where tstop is the stopping time of particle and ΩK is the Keplerian orbital frequency. This is because the smaller dust particles are more sensitive to the gas flow.
The gas flow induced by low-mass planets can be considered as one of the possible origins of the observed dust substructuers in disks. The characteristics of the dust ring and gap formed by the planet-induced gas flow are summarized as follows:
1. The planet-induced gas flow forms the ring and (or) gap in the distribution of aerodynamically small dust grains, St≦10-3.
2. The gas flow induced by a low-mass embedded planet can generate the dust ring and (or) gap in the vicinity of the planet location without creating gas gap or pressure bump.
Based on our results, we discuss the implications for the existence of the distant low-mass planets.
References:
Andrews, S. M., Huang, J., Pérez, L. M., et al. 2018, The Astrophysical Journal Letters, 869, L41
Zhang, K., Booth, A. S., Law, C. J., et al. 2021, The Astrophysical Journal Supplement Series, 257, 5
Jiang, H., Zhu, W., & Ormel, C. W. 2021, arXiv preprint arXiv:2112.13859
Ormel, C. W., Shi, J.-M., & Kuiper, R. 2015, MNRAS, 447, 3512
Fung, J., Artymowicz, P., & Wu, Y. 2015, ApJ, 811, 101
Kuwahara, A. & Kurokawa, H. 2020a, A&A, 633, A81
Kuwahara, A. & Kurokawa, H. 2020b, A&A, 643, A21