Oliver Gressel
YOU?
Author Swipe
View article: Self-gravity in thin protoplanetary discs: 1. The smoothing-length approximation versus the exact self-gravity kernel
Self-gravity in thin protoplanetary discs: 1. The smoothing-length approximation versus the exact self-gravity kernel Open
Planet-forming discs often contain structures like spiral arms, typically linked to the disc's gravitational forces. In 2D models, an ad hoc softening prescription is commonly used for self-gravity, but this overlooks the vertical structur…
View article: Gravito-turbulent bi-fluid protoplanetary discs
Gravito-turbulent bi-fluid protoplanetary discs Open
Context . In Class 0 and I as well as in the outskirts of Class II circumstellar discs, the self-gravity of gas is expected to be significant, which certainly impacts the disc vertical hydrostatic equilibrium. Notably, the contribution of …
View article: Global Hall-magnetohydrodynamic simulations of transition disks
Global Hall-magnetohydrodynamic simulations of transition disks Open
Context. Transition disks (TDs) are a type of protoplanetary disk characterized by a central dust and gas cavity. The processes behind how these cavities are formed and maintained, along with their observed high accretion rates of 10 −8 −1…
View article: Global Hall-magnetohydrodynamic simulations of transition disks
Global Hall-magnetohydrodynamic simulations of transition disks Open
Context. Transition disks (TDs) are a type of protoplanetary disk characterized by a central dust and gas cavity. The processes behind how these cavities are formed and maintained, along with their observed high accretion rates of $10^{-8}…
View article: Toward an efficient second‐order method for computing the surface gravitational potential on spherical‐polar meshes
Toward an efficient second‐order method for computing the surface gravitational potential on spherical‐polar meshes Open
Astrophysical accretion discs that carry a significant mass compared with their central object are subject to the effect of self‐gravity. In the context of circumstellar discs, this can, for instance, cause fragmentation of the disc gas, a…
View article: Hall-magnetohydrodynamic simulations of X-ray photoevaporative protoplanetary disc winds
Hall-magnetohydrodynamic simulations of X-ray photoevaporative protoplanetary disc winds Open
Understanding the evolution and dispersal via energetic stellar radiation of protoplanetary discs (PPDs) is a prominent challenge in astrophysics. It has been established that X-ray luminosity from the central protostar can significantly h…
View article: Hall-magnetohydrodynamic simulations of X-ray photoevaporative protoplanetary disc winds
Hall-magnetohydrodynamic simulations of X-ray photoevaporative protoplanetary disc winds Open
Understanding the complex evolution of protoplanetary disks (PPDs) and their dispersal via energetic stellar radiation are prominent challenges in astrophysics. It has recently been established that specifically the X-ray luminosity from t…
View article: Alpha tensor and dynamo excitation in turbulent fluids with anisotropic conductivity fluctuations
Alpha tensor and dynamo excitation in turbulent fluids with anisotropic conductivity fluctuations Open
A mean‐field theory of the electrodynamics of a turbulent fluid is formulated under the assumption that the molecular electric conductivity is correlated with the turbulent velocity fluctuation in the (radial) direction, . It is shown that…
View article: Finite-time Response of Dynamo Mean-field Effects in Magnetorotational Turbulence
Finite-time Response of Dynamo Mean-field Effects in Magnetorotational Turbulence Open
Accretion disk turbulence along with its effect on large-scale magnetic fields plays an important role in understanding disk evolution in general, and the launching of astrophysical jets in particular. Motivated by enabling a comprehensive…
View article: The Role of Disk Winds in the Evolution and Dispersal of Protoplanetary Disks
The Role of Disk Winds in the Evolution and Dispersal of Protoplanetary Disks Open
The assembly and architecture of planetary systems strongly depend on the physical processes governing the evolution and dispersal of protoplanetary disks. Since Protostars and Planets VI, new observations and theoretical insights favor di…
View article: Finite-time response of dynamo mean-field effects in magnetorotational turbulence
Finite-time response of dynamo mean-field effects in magnetorotational turbulence Open
Accretion disc turbulence along with its effect on large-scale magnetic fields plays an important role in understanding disc evolution in general, and the launching of astrophysical jets in particular. Motivated by enabling a comprehensive…
View article: On the combined role of cosmic rays and supernova-driven turbulence for galactic dynamos
On the combined role of cosmic rays and supernova-driven turbulence for galactic dynamos Open
Large-scale coherent magnetic fields observed in the nearby galaxies are thought to originate by a mean-field dynamo. This is governed via the turbulent electromotive force (EMF, $\overline{{\boldsymbol {\cal E}} {}}$) generated by the hel…
View article: On the spatial and temporal non-locality of dynamo mean-field effects in supersonic interstellar turbulence
On the spatial and temporal non-locality of dynamo mean-field effects in supersonic interstellar turbulence Open
The interstellar medium (ISM) of the Milky Way and nearby disc galaxies harbour large-scale coherent magnetic fields of microgauss strength, that can be explained via the action of a mean-field dynamo. As in our previous work, we aim to qu…
View article: Low-mass planet migration in three-dimensional wind-driven inviscid discs: a negative corotation torque
Low-mass planet migration in three-dimensional wind-driven inviscid discs: a negative corotation torque Open
We present simulations of low-mass planet–disc interactions in inviscid three-dimensional discs. We show that a wind-driven laminar accretion flow through the surface layers of the disc does not significantly modify the migration torque ex…
View article: Turbulent transport coefficients in galactic dynamo simulations using singular value decomposition
Turbulent transport coefficients in galactic dynamo simulations using singular value decomposition Open
Coherent magnetic fields in disc galaxies are thought to be generated by a large-scale (or mean-field) dynamo operating in their interstellar medium. A key driver of mean magnetic field growth is the turbulent electromotive force (EMF), wh…
View article: Planet formation: The case for large efforts on the computational side
Planet formation: The case for large efforts on the computational side Open
Modern astronomy has finally been able to observe protoplanetary disks in reasonable resolution and detail, unveiling the processes happening during planet formation. These observed processes are understood under the framework of disk-plan…
View article: Low mass planet migration in Hall-affected disks
Low mass planet migration in Hall-affected disks Open
Recent developments in non-ideal magnetohydrodynamic simulations of protoplanetary disks suggest that instead of being traditional turbulent (viscous) accretion disks, they have a largely laminar flow with accretion driven by large-scale w…
View article: Low mass planet migration in magnetically torqued dead zones – I. Static migration torque
Low mass planet migration in magnetically torqued dead zones – I. Static migration torque Open
Motivated by models suggesting that the inner planet forming regions of protoplanetary discs are predominantly lacking in viscosity-inducing turbulence, and are possibly threaded by Hall-effect generated large-scale horizontal magnetic fie…
View article: Toward realistic simulations of magneto-thermal winds from weakly-ionized protoplanetary disks
Toward realistic simulations of magneto-thermal winds from weakly-ionized protoplanetary disks Open
Protoplanetary disks (PPDs) accrete onto their central T Tauri star via\nmagnetic stresses. When the effect of ambipolar diffusion (AD) is included, and\nin the presence of a vertical magnetic field, the disk remains laminar between\n1-5 a…
View article: MISALIGNED DISKS IN THE BINARY PROTOSTAR IRS 43
MISALIGNED DISKS IN THE BINARY PROTOSTAR IRS 43 Open
Recent high angular resolution ( ) ALMA observations of the 1.1 mm continuum and of HCO + J = 3–2 and HCN J = 3–2 gas toward the binary protostar IRS 43 reveal multiple Keplerian disks that are significantly misaligned ( ), both in inclina…
View article: Linear analysis of the vertical shear instability: outstanding issues and improved solutions
Linear analysis of the vertical shear instability: outstanding issues and improved solutions Open
\n Context. The vertical shear instability is one of several known mechanisms that are potentially active in the so-called dead zones of protoplanetary accretion disks. A recent analysis of the instability mechanism indicates that a subset…