Standing on the shoulders of giants : Trojan Earths and vortex trapping in low mass self-gravitating protoplanetary disks of gas and solids

By Wladimir Lyra, Anders Johansen, H. Klahr, N. Piskunov. 2008

136 citations recorded by the source corpus.

Context. Centimeter and meter-sized solid particles in protoplanetary disks are trapped within long-lived, high-pressure regions, creating opportunities for collapse into planetesimals and planetary embryos. Aims. We aim to study the effect of the high-pressure regions generated in the gaseous disks by a giant planet perturber. These regions consist of gas retained in tadpole orbits around the stable Lagrangian points as a gap is carved, and the Rossby vortices launched at the edges of the gap. Methods. We performed global simulations of the dynamics of gas and solids in a low mass non-magnetized self-gravitating thin protoplanetary disk. We employed the Pencil code to solve the Eulerian hydro equations, tracing the solids with a large number of Lagrangian particles, usually 100 000. To compute the gravitational potential of the swarm of solids, we solved the Poisson equation using particle-mesh methods with multiple fast Fourier transforms. Results. Huge particle concentrations are seen in the Lagrangian points of the giant planet, as well as in the vortices they induce at the edges of the carved gaps. For 1 cm to 10 cm radii, gravitational collapse occurs in the Lagrangian points in less than 200 orbits. For 5 cm particles, a 2$M_{\oplus}$ planet is formed. For 10 cm, the final maximum collapsed mass is around 3$M_{\oplus}$. The collapse of the 1 cm particles is indirect, following the timescale of gas depletion from the tadpole orbits. Vortices are excited at the edges of the gap, primarily trapping particles of 30 cm radii. The rocky planet that is formed is as massive as 17$M_{\oplus}$, constituting a Super-Earth. Collapse does not occur for 40 cm onwards. By using multiple particle species, we find that gas drag modifies the streamlines in the tadpole region around the classical L4 and L5 points. As a result, particles of different radii have their stable points shifted to different locations. Collapse therefore takes longer and produces planets of lower mass. Three super-Earths are formed in the vortices, the most massive having 4.5$M_{\oplus}$. Conclusions. A Jupiter-mass planet can induce the formation of other planetary embryos at the outer edge of its gas gap. Trojan Earth-mass planets are readily formed; although not existing in the solar system, might be common in the exoplanetary zoo.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/149adb57ac729e20b7516ee1eec19049babb15e1

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Spectroscopy

Citations in the corpus

Multiple Disk Gaps and Rings Generated by a Single Super-Earth (2017, methodology): “The behavior of dust in a disk with a sub-Jupiter mass planet has been investigated by many others (e.g., Paardekooper & Mellema 2004, 2006; Lyra et al. 2009; Zhu et al. 2014; Rosotti et al. 2016) using two-fluid simulations.”
The Disk Substructures at High Angular Resolution Project (DSHARP). VII. The Planet–Disk Interactions Interpretation (2018, unknown): “(3) The dust concentration at L5 or both L4/L5 is seen in some α=10−4 cases, consistent with previous simulations (Lyra et al. 2009).”
ALMA unveils rings and gaps in the protoplanetary system HD 169142: signatures of two giant protoplanets (2017, background): “Such an asymmetry is thought to be due to dynamical interaction between the disk and a massive planet generating a vortex where dust particles are trapped (Rossby instability, de Val-Borro et al. 2007; Lyra et al. 2009).”
Dust Evolution and the Formation of Planetesimals (2016, background): “…caused by the magnetorotational instability and the “dead zone” whose ionization fraction is too low to sustain the magnetorotational instability has been shown to lead to the formation of pressure bumps at the inside and outside of the dead zone (Lyra et al. 2008, 2009; Kretke et al. 2009).”
Gaps, Rings, and Non-Axisymmetric Structures in Protoplanetary Disks - From Simulations to ALMA Observations (2014, background): “Another possibility was presented by Varnière & Tagger (2006), Lyra et al. (2009a), Regály et al. (2012), and Faure et al. (2014): the surface density enhancement and following vortex formation was generated by the increase of accretion stress in the outer disk caused by the…”