scholarly journals Planetesimal formation in an evolving protoplanetary disk with a dead zone

2019 ◽  
Vol 627 ◽  
pp. A50 ◽  
Author(s):  
Sébastien Charnoz ◽  
Francesco C. Pignatale ◽  
Ryuki Hyodo ◽  
Brandon Mahan ◽  
Marc Chaussidon ◽  
...  
Keyword(s):  
Thermal Evolution ◽  
Dead Zone ◽  
Protoplanetary Disk ◽  
Outer Edge ◽  
Positive Pressure ◽  
Disk Model ◽  
Dust Transport ◽  
Dust Trap ◽  
Streaming Instability ◽  
Snow Line

Context. When and where planetesimals form in a protoplanetary disk are highly debated questions. Streaming instability is considered the most promising mechanism, but the conditions for its onset are stringent. Disk studies show that the planet forming region is not turbulent because of the lack of ionization forming possibly dead zones (DZs). Aims. We investigate planetesimal formation in an evolving disk, including the DZ and thermal evolution. Methods. We used a 1D time-evolving stratified disk model with composite chemistry grains, gas and dust transport, and dust growth. Results. Accretion of planetesimals always develops in the DZ around the snow line, due to a combination of water recondensation and creation of dust traps caused by viscosity variations close to the DZ. The width of the planetesimal forming region depends on the disk metallicity. For Z = Z⊙, planetesimals form in a ring of about 1 au width, while for Z > 1.2 Z⊙ planetesimals form from the snow line up to the outer edge of the DZ ≃ 20 au. The efficiency of planetesimal formation in a disk with a DZ is due to the very low effective turbulence in the DZ and to the efficient piling up of material coming from farther away; this material accumulates in region of positive pressure gradients forming a dust trap due to viscosity variations. For Z = Z⊙ the disk is always dominated in terms of mass by pebbles, while for Z > 1.2 Z⊙ planetesimals are always more abundant than pebbles. If it is assumed that silicate dust is sticky and grows up to impact velocities ~10 m s−1, then planetesimals can form down to 0.1 au (close to the inner edge of the DZ). In conclusion the DZ seems to be a sweet spot for the formation of planetesimals: wide scale planetesimal formation is possible for Z > 1.2 Z⊙. If hot silicate dust is as sticky as ice, then it is also possible to form planetesimals well inside the snow line.

scholarly journals EVIDENCE FOR A SNOW LINE BEYOND THE TRANSITIONAL RADIUS IN THE TW Hya PROTOPLANETARY DISK

2013 ◽  
Vol 766 (2) ◽  
pp. 82 ◽  
Author(s):  
K. Zhang ◽  
K. M. Pontoppidan ◽  
C. Salyk ◽  
G. A. Blake
Keyword(s):  
Protoplanetary Disk ◽  
Snow Line

Characteristics of an hybrid atmosphere with disk-captured and degassing contributions over a rocky planet’s magma ocean. A modeling approach.

2020 ◽  
Author(s):  
Athanasia Nikolaou ◽  
Lorenzo Mugnai ◽  
Oliver Herbort ◽  
Enzo Pascale ◽  
Peter Woitke
Keyword(s):  
Thermal Evolution ◽  
Chemical Characterization ◽  
Protoplanetary Disk ◽  
International Institute ◽  
Atmospheric Conditions ◽  
Magma Ocean ◽  
Silicate Mineral ◽  
Chemical Abundances ◽  
Magma Oceans ◽  
The University

<p>Motivation:<br />   Early during their formation the planets capture an amount of atmosphere from the protoplanetary disk (Ikoma et al. 2018, Odert et al. 2018, Lammer et al. 2020, Kimura and Ikoma 2020). An additional proportion of their atmosphere is provided during the magma ocean stage by interior degassing. The latter mechanism is assumed to be the main provider of the final atmospheric mass. Its composition is compromised by the source silicate mineral and its chemical characterization (Gaillard and Scaillet 2014, Herbort et al. 2020).<br />   Numerous studies support the degassing of the oxidized gas species H<sub>2</sub>O and CO<sub>2</sub> as main contributions from the magma ocean phase (Abe and Matsui 1988, Abe 1993, Elkins-Tanton 2008, Schaefer et al. 2012, Lebrun et al. 2013, Lupu et al. 2014, Gaillard and Scaillet 2014, Salvador et al. 2017, Nikolaou et al. 2019). Previous work has also shown that H<sub>2</sub>O, in particular, plays a crucial role (Hamano et al. 2013, Katyal et al. 2019, Turbet et al. 2019) in thermal blanketing. H<sub>2</sub>O possibly leads to “long-term” (Hamano et al 2013) or “conditionally continuous” (Nikolaou et al. 2019) magma oceans that effectively cease to cool. Water also ties directly to the availability of hydrogen that drives hydrodynamic escape (Airapetian et al. 2017, Lammer et al. 2018). CO<sub>2 </sub>factors into both above processes, as well (Wordsworth and Pierrehumbert 2013, Odert et al. 2018). Constraining the H<sub>2</sub>O and CO<sub>2</sub> abundances early after formation is indispensible to the planet’s thermal evolution and extensive modeling effort has been devoted to it. Their constraint would in particular help revisit which magma ocean types among transient-conditionally continuous-permanent (Nikolaou et al. 2019) are detectable in future exoplanetary missions (ARIEL, Tinetti et al. 2018; PLATO, Rauer et al. 2014).<br /> </p> <p>Method:<br />   In this work we focus on the combination of degassed and disk-captured atmosphere under the assumption of chemical equilibrium. Using simulations from the 1D Convective Ocean of Magma Radiative Atmosphere and Degassing model (Nikolaou et al. 2019) we obtain the thermal evolution and degassing tracks of a rocky planet. In order to evaluate the chemical abundances under equilibrium conditions we employ the thermodynamical model GGchem (Woitke et al. 2018).<br />   We explore the atmospheric conditions during the lifetime of a magma ocean under varying mineral compositions and protoplanetary disk contributions. We discuss the results in the context of the likely magma ocean types.<br /> <br />A.N. and P.W. wish to thank the Erwin Schrödinger International Institute for Mathematics and Physics (ESI) of the University of Vienna, Thematic Programme on “Astrophysical Origins: Pathways from Star Formation to Habitable Planets” 2019, which enabled this collaboration.</p>

scholarly journals Diffusion and Concentration of Solids in the Dead Zone of a Protoplanetary Disk

2018 ◽  
Vol 868 (1) ◽  
pp. 27 ◽  
Author(s):  
Chao-Chin Yang ◽  
Mordecai-Mark Mac Low ◽  
Anders Johansen
Keyword(s):  
Dead Zone ◽  
Protoplanetary Disk ◽  
The Dead

THE EVOLUTION OF THE SNOW LINE IN A PROTOPLANETARY DISK

2015 ◽  
Vol 802 (1) ◽  
pp. 58 ◽  
Author(s):  
Yu Zhang ◽  
Liping Jin
Keyword(s):  
Protoplanetary Disk ◽  
Snow Line

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 Dust Transport and Processing in Centrifugally Driven Protoplanetary Disk Winds

2019 ◽  
Vol 882 (1) ◽  
pp. 33 ◽  
Author(s):  
Steven Giacalone ◽  
Seth Teitler ◽  
Arieh Königl ◽  
Sebastiaan Krijt ◽  
Fred J. Ciesla
Keyword(s):  
Protoplanetary Disk ◽  
Dust Transport

scholarly journals Efficiency of radial transport of ices in protoplanetary disks probed with infrared observations: the case of CO2

2018 ◽  
Vol 611 ◽  
pp. A80 ◽  
Author(s):  
Arthur D. Bosman ◽  
Alexander G. G. M. Tielens ◽  
Ewine F. van Dishoeck
Keyword(s):  
Grain Growth ◽  
Solid Material ◽  
Gas Diffusion ◽  
Transport Processes ◽  
X Rays ◽  
Radial Transport ◽  
Disk Model ◽  
Dust Transport ◽  
Destruction Rate ◽  
Gas Accretion

Context. Radial transport of icy solid material from the cold outer disk to the warm inner disk is thought to be important for planet formation. However, the efficiency at which this happens is currently unconstrained. Efficient radial transport of icy dust grains could significantly alter the composition of the gas in the inner disk, enhancing the gas-phase abundances of the major ice constituents such as H2O and CO2.Aim. Our aim is to model the gaseous CO2 abundance in the inner disk and use this to probe the efficiency of icy dust transport in a viscous disk. From the model predictions, infrared CO2 spectra are simulated and features that could be tracers of icy CO2, and thus dust, radial transport efficiency are investigated.Methods. We have developed a 1D viscous disk model that includes gas accretion and gas diffusion as well as a description for grain growth and grain transport. Sublimation and freeze-out of CO2 and H2O has been included as well as a parametrisation of the CO2 chemistry. The thermo-chemical code DALI was used to model the mid-infrared spectrum of CO2, as can be observed with JWST-MIRI.Results. CO2 ice sublimating at the iceline increases the gaseous CO2 abundance to levels equal to the CO2 ice abundance of ~10−5, which is three orders of magnitude more than the gaseous CO2 abundances of ~10−8 observed by Spitzer. Grain growth and radial drift increase the rate at which CO2 is transported over the iceline and thus the gaseous CO2 abundance, further exacerbating the problem. In the case without radial drift, a CO2 destruction rate of at least 10−11 s−1 or a destruction timescale of at most 1000 yr is needed to reconcile model prediction with observations. This rate is at least two orders of magnitude higher than the fastest destruction rate included in chemical databases. A range of potential physical mechanisms to explain the low observed CO2 abundances are discussed.Conclusions. We conclude that transport processes in disks can have profound effects on the abundances of species in the inner disk such as CO2. The discrepancy between our model and observations either suggests frequent shocks in the inner 10 AU that destroy CO2, or that the abundant midplane CO2 is hidden from our view by an optically thick column of low abundance CO2 due to strong UV and/or X-rays in the surface layers. Modelling and observations of other molecules, such as CH4 or NH3, can give further handles on the rate of mass transport.

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