scholarly journals Formation of planetary populations − II. Effects of initial disc size and radial dust drift

2020 ◽  
Vol 493 (1) ◽  
pp. 1013-1033 ◽  
Author(s):  
Matthew Alessi ◽  
Ralph E Pudritz ◽  
Alex J Cridland
Keyword(s):  
Planet Formation ◽  
Dead Zone ◽  
Outer Edge ◽  
Type I ◽  
Population Synthesis ◽  
The Dead ◽  
Dust Evolution ◽  
Disc Size ◽  
Heat Transition

ABSTRACT Recent ALMA observations indicate that while a range of disc sizes exist, typical disc radii are small, and that radial dust drift affects the distribution of solids in discs. Here, we explore the consequences of these features in planet population synthesis models. A key feature of our model is planet traps – barriers to otherwise rapid type-I migration of forming planets – for which we include the ice line, heat transition, and outer edge of the dead zone. We find that the ice line plays a fundamental role in the formation of warm Jupiters. In particular, the ratio of super Earths to warm Jupiters formed at the ice line depends sensitively on the initial disc radius. Initial gas disc radii of ∼50 au results in the largest super Earth populations, while both larger and smaller disc sizes result in the ice line producing more gas giants near 1 au. This transition between typical planet class formed at the ice line at various disc radii confirms that planet formation is fundamentally linked to disc properties (in this case, disc size), and is a result that is only seen when dust evolution effects are included in our models. Additionally, we find that including radial dust drift results in the formation of more super Earths between 0.1 and 1 au, having shorter orbital radii than those produced in models where dust evolution effects are not included.

scholarly journals Dead zones and the diversity of exoplanetary systems

2010 ◽  
Vol 6 (S276) ◽  
pp. 430-431
Author(s):  
Yasuhiro Hasegawa ◽  
Ralph E. Pudritz
Keyword(s):  
Dead Zone ◽  
Outer Edge ◽  
Type I ◽  
Density Region ◽  
Radial Gradient ◽  
Exoplanetary Systems ◽  
Disk Evolution ◽  
High Density Region ◽  
The Dead ◽  
Planetary Migration

AbstractPlanetary migration provides a theoretical basis for the observed diversity of exoplanetary systems. We demonstrate that dust settling - an inescapable feature of disk evolution - gives even more rapid type I migration by up to a factor of about 2 than occurs in disks with fully mixed dust. On the other hand, type II migration becomes slower by a factor of 2 due to dust settling. This even more problematic type I migration can be resolved by the presence of a dead zone; the inner, high density region of a disk which features a low level of turbulence. We show that enhanced dust settling in the dead zone leaves a dusty wall at its outer edge. Back-heating of the dead zone by this wall produces a positive radial gradient for the disk temperature, which acts as a barrier for type I migration.

scholarly journals On the vortex evolution in non-isothermal protoplanetary discs

2020 ◽  
Vol 493 (2) ◽  
pp. 3014-3025
Author(s):  
D Tarczay-Nehéz ◽  
Zs Regály ◽  
E Vorobyov
Keyword(s):  
Large Scale ◽  
Planet Formation ◽  
Dead Zone ◽  
Giant Planet ◽  
Building Blocks ◽  
Outer Edge ◽  
Wave Instability ◽  
Large Scale Vortex ◽  
Self Gravity ◽  
Protoplanetary Discs

ABSTRACT It is believed that large-scale horseshoe-like brightness asymmetries found in dozens of transitional protoplanetary discs are caused by anticyclonic vortices. These vortices can play a key role in planet formation, as mm-sized dust – the building blocks of planets – can be accumulated inside them. Anticyclonic vortices are formed by the Rossby wave instability, which can be excited at the gap edges opened by a giant planet or at sharp viscosity transitions of accretionally inactive regions. It is known that vortices are prone to stretching and subsequent dissolution due to disc self-gravity for canonical disc masses in the isothermal approximation. To improve the hydrodynamic model of protoplanetary discs, we include the disc thermodynamics in our model. In this paper, we present our results on the evolution of the vortices formed at the outer edge of an accretionally inactive region (dead zone) assuming an ideal equation of state and taking PdV work, disc cooling in the β-approximation, and disc self-gravity into account. Thermodynamics affects the offset and the mode number (referring to the number of small vortices at the early phase) of the RWI excitation, as well as the strength, shape, and lifetime of the large-scale vortex formed through merging of the initial small vortices. We found that the inclusion of gas thermodynamics results in stronger, however decreased lifetime vortices. Our results suggest that a hypothetical vortex-aided planet formation scenario favours effectively cooling discs.

scholarly journals Planet formation bursts at the borders of the dead zone in 2D numerical simulations of circumstellar disks

2009 ◽  
Vol 497 (3) ◽  
pp. 869-888 ◽  
Author(s):  
W. Lyra ◽  
A. Johansen ◽  
A. Zsom ◽  
H. Klahr ◽  
N. Piskunov
Keyword(s):  
Numerical Simulations ◽  
Planet Formation ◽  
Dead Zone ◽  
Circumstellar Disks ◽  
The Dead

scholarly journals INSIDE-OUT PLANET FORMATION. III. PLANET–DISK INTERACTION AT THE DEAD ZONE INNER BOUNDARY

2015 ◽  
Vol 816 (1) ◽  
pp. 19 ◽  
Author(s):  
Xiao Hu(胡晓) ◽  
Zhaohuan Zhu(朱照寰) ◽  
Jonathan C. Tan ◽  
Sourav Chatterjee
Keyword(s):  
Planet Formation ◽  
Dead Zone ◽  
The Dead ◽  
Inside Out

scholarly journals Are the observed gaps in protoplanetary discs caused by growing planets?

2019 ◽  
Vol 488 (3) ◽  
pp. 3625-3633 ◽  
Author(s):  
N Ndugu ◽  
B Bitsch ◽  
E Jurua
Keyword(s):  
Planet Formation ◽  
Dust Particles ◽  
Type I ◽  
Type Ii ◽  
Population Synthesis ◽  
Small Pressure ◽  
Planetary Mass ◽  
Planet Migration ◽  
Gas Accretion ◽  
Protoplanetary Discs

ABSTRACT Recent detailed observations of protoplanetary discs revealed a lot of substructures that are mostly ring like. One interpretation is that these rings are caused by growing planets. These potential planets are not yet opening very deep gaps in their discs. These planets instead form small gaps in the discs to generate small pressure bumps exterior to their orbits that stop the inflow of the largest dust particles. In the pebble accretion paradigm, this planetary mass corresponds to the pebble isolation mass, where pebble accretion stops and efficient gas accretion starts. We perform planet population synthesis via pebble and gas accretion including type-I and type-II migration. In the first stage of our simulations, we investigate the conditions necessary for planets to reach the pebble isolation mass and compare their position to the observed gaps. We find that in order to match the gap structures 2000ME in pebbles is needed, which would be only available for the most metal-rich stars. We then follow the evolution of these planets for a few Myr to compare the resulting population with the observed exoplanet populations. Planet formation in discs with these large amounts of pebbles results in mostly forming gas giants and only very little super-Earths, contradicting observations. This leads to the conclusions that either (i) the observed discs are exceptions, (ii) not all gaps in observed discs are caused by planets, or (iii) that we miss some important ingredients in planet formation related to gas accretion and/or planet migration.

Improved Pole-placement Control with Feed-forward Dead Zone Compensation for Position Tracking of Electro-Pneumatic Actuator System Improved Pole-placement Control with Feed-forward Dead Zone Compensation for Position Tracking of Electro-Pneumatic Actuato

2021 ◽  
Vol 20 (2) ◽  
pp. 25-32
Author(s):  
Noorhazirah Sunar ◽  
Mohd Fua’ad Rahmat ◽  
Ahmad ‘Athif Mohd Fauzi ◽  
Zool Hilmi Ismail ◽  
Siti Marhanis Osman ◽  
...  
Keyword(s):  
Dead Zone ◽  
Pneumatic Actuator ◽  
Pole Placement ◽  
Position Tracking ◽  
Zone Model ◽  
Feed Forward ◽  
The Dead ◽  
Chattering Effect ◽  
Pole Placement Controller ◽  
Pole Placement Control

Dead-zone in the valve degraded the performances of the Electro-Pneumatic Actuator (EPA) system.  It makes the system difficult to control, become unstable and leads to chattering effect nearest desired position.  In order to cater this issue, the EPA system transfer function and the dead-zone model is identified by MATLAB SI toolbox and the Particle Swarm Optimization (PSO) algorithm respectively.  Then a parametric control is designed based on pole-placement approach and combine with feed-forward inverse dead-zone compensation.  To reduce chattering effect, a smooth parameter is added to the controller output.  The advantages of using these techniques are the chattering effect and the dead-zone of the EPA system is reduced.  Moreover, the feed-forward system improves the transient performance.  The results are compared with the pole-placement control (1) without compensator and (2) with conventional dead-zone compensator.  Based on the experimental results, the proposed controller reduced the chattering effect due to the controller output of conventional dead-zone compensation, 90% of the pole-placement controller steady-state error and 30% and 40% of the pole-placement controller with conventional dead-zone compensation settling time and rise time.

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