scholarly journals Global 3D radiation hydrodynamic simulations of proto-Jupiter’s convective envelope

2021 ◽  
Author(s):  
Zhaohuan Zhu ◽  
Yan-Fei Jiang ◽  
Hans Baehr ◽  
Andrew N Youdin ◽  
Philip J Armitage ◽  
...  
Keyword(s):  
Thermal Structure ◽  
Giant Planet ◽  
Convective Motion ◽  
Passive Scalar ◽  
Chemical Abundances ◽  
Convective Envelope ◽  
Hydrodynamic Simulations ◽  
1D Model ◽  
3D Effects ◽  
Core Accretion

Abstract The core accretion model of giant planet formation has been challenged by the discovery of recycling flows between the planetary envelope and the disc that can slow or stall envelope accretion. We carry out 3D radiation hydrodynamic simulations with an updated opacity compilation to model the proto-Jupiter’s envelope. To isolate the 3D effects of convection and recycling, we simulate both isolated spherical envelopes and envelopes embedded in discs. The envelopes are heated at given rates to achieve steady states, enabling comparisons with 1D models. We vary envelope properties to obtain both radiative and convective solutions. Using a passive scalar, we observe significant mass recycling on the orbital timescale. For a radiative envelope, recycling can only penetrate from the disc surface until ∼0.1-0.2 planetary Hill radii, while for a convective envelope, the convective motion can ‘dredge up’ the deeper part of the envelope so that the entire convective envelope is recycled efficiently. This recycling, however, has only limited effects on the envelopes’ thermal structure. The radiative envelope embedded in the disc has identical structure as the isolated envelope. The convective envelope has a slightly higher density when it is embedded in the disc. We introduce a modified 1D approach which can fully reproduce our 3D simulations. With our updated opacity and 1D model, we recompute Jupiter’s envelope accretion with a 10 M⊕ core, and the timescale to runaway accretion is shorter than the disc lifetime as in prior studies. Finally, we discuss the implications of the efficient recycling on the observed chemical abundances of the planetary atmosphere (especially for super-Earths and mini-Neptunes).

scholarly journals The likelihood of detecting young giant planets with high-contrast imaging and interferometry

2019 ◽  
Vol 490 (1) ◽  
pp. 502-512 ◽  
Author(s):  
A L Wallace ◽  
M J Ireland
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Giant Planet ◽  
Giant Planets ◽  
Contrast Imaging ◽  
Distribution Models ◽  
High Contrast Imaging ◽  
Solar Type ◽  
Infrared Wavelengths ◽  
Core Accretion

ABSTRACT Giant planets are expected to form at orbital radii that are relatively large compared to transit and radial velocity detections (>1 au). As a result, giant planet formation is best observed through direct imaging. By simulating the formation of giant (0.3–5MJ) planets by core accretion, we predict planet magnitude in the near-infrared (2–4 μm) and demonstrate that, once a planet reaches the runaway accretion phase, it is self-luminous and is bright enough to be detected in near-infrared wavelengths. Using planet distribution models consistent with existing radial velocity and imaging constraints, we simulate a large sample of systems with the same stellar and disc properties to determine how many planets can be detected. We find that current large (8–10 m) telescopes have at most a 0.2 per cent chance of detecting a core-accretion giant planet in the L’ band and 2 per cent in the K band for a typical solar-type star. Future instruments such as METIS and VIKiNG have higher sensitivity and are expected to detect exoplanets at a maximum rate of 2 and 8 per cent, respectively.

Reinforcement of the link between stellar metallicity and the zero age orbit of gas giant planet

2017 ◽  
Vol 13 (S332) ◽  
pp. 109-112
Author(s):  
Rafael Pinotti ◽  
Heloisa M. Boechat-Roberty ◽  
Gustavo F. Porto de Mello
Keyword(s):  
Extrasolar Planets ◽  
Giant Planet ◽  
Gas Temperature ◽  
Radial Profiles ◽  
Accretion Model ◽  
Order Of Magnitude ◽  
Gas Giant ◽  
Core Accretion ◽  
Magnitude Increase ◽  
Dust Surface

AbstractIn 2005 we suggested a relation between the optimal locus of gas giant planet formation, prior to migration, and the metallicity of the host star, based on the core accretion model, and radial profiles of dust surface density and gas temperature. At that time, less than 200 extrasolar planets were known, limiting the scope of our analysis. Here, we take into account the expanded statistics allowed by new discoveries, in order to check the validity of some premises. We compare predictions with the present available data and results for different stellar mass ranges. We find that the zero age planetary orbit (ZAPO) hypothesis continues to hold after a two order of magnitude increase in discovered planets, as well as the prediction that planets around metal poor stars would have shorter orbits.

The formation of a gas giant planet in a viscously evolved protoplanetary disk within the core accretion model

2018 ◽  
Vol 363 (9) ◽  
Author(s):  
Chunjian Liu ◽  
Qing Ai ◽  
Zhen Yao ◽  
Hualian Tian ◽  
Jiayun Shen ◽  
...  
Keyword(s):  
Giant Planet ◽  
Protoplanetary Disk ◽  
The Core ◽  
Accretion Model ◽  
Gas Giant ◽  
Core Accretion

scholarly journals Convection Theory and Relevant Problems in Stellar Structure, Evolution, and Pulsational Stability I Convection Theory and Structure of Convection Zone and Stellar Evolution

2021 ◽  
Vol 7 ◽  
Author(s):  
Da-run Xiong
Keyword(s):  
Main Sequence ◽  
Massive Stars ◽  
Thermal Structure ◽  
Stellar Structure ◽  
Temperature Fields ◽  
Structure Evolution ◽  
The Sun ◽  
Convective Envelope ◽  
Sequence Band ◽  
Lithium Depletion

A non-local and time-dependent theory of convection was briefly described. This theory was used to calculate the structure of solar convection zones, the evolution of massive stars, lithium depletion in the atmosphere of the Sun and late-type dwarfs, and stellar oscillations (in Part Ⅱ). The results show that: 1) the theoretical turbulent velocity and temperature fields in the atmosphere and the thermal structure of the convective envelope of the Sun agree with the observations and inferences from helioseismic inversion very well. 2) The so-called semi-convection contradiction in the evolutionary calculations of massive stars was removed automatically, as predicted by us. The theoretical evolution tracks of massive stars run at higher luminosity and the main sequence band becomes noticeably wider in comparison with those calculated using the local mixing-length theory (MLT). This means that the evolutionary mass for a given luminosity was overestimated and the width of the main sequence band was underestimated by the local MLT, which may be part of the reason for the contradiction between the evolutionary and pulsational masses of Cepheid variables and the contradiction between theoretical and observed distributions of luminous stars in the H-R diagram. 3) The predicted lithium depletion, in general, agrees well with the observation of the Sun and Galactic open clusters of different ages. 4) Our theoretical results for non-adiabatic oscillations are in good agreement with the observed mode instability from classic variables of high-luminosity red giants. Almost all the instability strips of the classical pulsating variables (including the Cepheid, δ Scuti, γ Doradus, βCephei, and SPB strips) were reproduced (Part Ⅱ).

scholarly journals Synthetic observations of turbulent flows in diffuse multiphase interstellar medium

2006 ◽  
Vol 2 (S237) ◽  
pp. 499-499
Author(s):  
Masako Yamada ◽  
H. Koyama ◽  
K. Omukai ◽  
S. Inutsuka
Keyword(s):  
Interstellar Medium ◽  
Turbulent Flows ◽  
Thermal Structure ◽  
Line Emission ◽  
High Ratio ◽  
Excitation Energies ◽  
Interstellar Clouds ◽  
Hydrodynamic Simulations ◽  
Non Local ◽  
Multi Phase

AbstractWe examined observational characteristics of multi-phase turbulent flows in the diffuse interstellar medium (ISM) by calculating atomic and molecular carbon lines. Radiation field maps of C+, C0, and CO line emissions were generated by calculating the non-local thermodynamic equilibrium (nonLTE) level populations and high resolution hydrodynamic simulations of diffuse ISM. By analyzing synthetic line emission, we found a high ratio between the lines of high- and low-excitation energies in the diffuse multi-phase interstellar medium. Our results shows that simultaneous observations of the lines of warm- and cold-gas tracers will be useful in examining the thermal structure, and hence the origin of diffuse interstellar clouds.

scholarly journals Composition of massive giant planets

2010 ◽  
Vol 6 (S276) ◽  
pp. 95-100
Author(s):  
Ravit Helled ◽  
Peter Bodenheimer ◽  
Jack J. Lissauer
Keyword(s):  
Large Range ◽  
Giant Planet ◽  
Giant Planets ◽  
Heavy Elements ◽  
Formation Model ◽  
The Core ◽  
Accretion Model ◽  
Low Mass ◽  
Core Accretion ◽  
Host Stars

AbstractThe two current models for giant planet formation are core accretion and disk instability. We discuss the core masses and overall planetary enrichment in heavy elements predicted by the two formation models, and show that both models could lead to a large range of final compositions. For example, both can form giant planets with nearly stellar compositions. However, low-mass giant planets, enriched in heavy elements compared to their host stars, are more easily explained by the core accretion model. The final structure of the planets, i.e., the distribution of heavy elements, is not firmly constrained in either formation model.

scholarly journals High-resolution spectroscopic view of planet formation sites

2010 ◽  
Vol 6 (S276) ◽  
pp. 50-53 ◽  
Author(s):  
Zsolt Regály ◽  
Laszlo Kiss ◽  
Zsolt Sándor ◽  
Cornelis P. Dullemond
Keyword(s):  
High Resolution ◽  
Planet Formation ◽  
Giant Planet ◽  
Circumstellar Disks ◽  
Disk Surface ◽  
Line Profiles ◽  
Molecular Line ◽  
Near Ir ◽  
Velocity Flow ◽  
Core Accretion

AbstractTheories of planet formation predict the birth of giant planets in the inner, dense, and gas-rich regions of the circumstellar disks around young stars. These are the regions from which strong CO emission is expected. Observations have so far been unable to confirm the presence of planets caught in formation. We have developed a novel method to detect a giant planet still embedded in a circumstellar disk by the distortions of the CO molecular line profiles emerging from the protoplanetary disk's surface. The method is based on the fact that a giant planet significantly perturbs the gas velocity flow in addition to distorting the disk surface density. We have calculated the emerging molecular line profiles by combining hydrodynamical models with semianalytic radiative transfer calculations. Our results have shown that a giant Jupiter-like planet can be detected using contemporary or future high-resolution near-IR spectrographs such as VLT/CRIRES or ELT/METIS. We have also studied the effects of binarity on disk perturbations. The most interesting results have been found for eccentric circumprimary disks in mid-separation binaries, for which the disk eccentricity - detectable from the asymmetric line profiles - arises from the gravitational effects of the companion star. Our detailed simulations shed new light on how to constrain the disk kinematical state as well as its eccentricity profile. Recent findings by independent groups have shown that core-accretion is severely affected by disk eccentricity, hence detection of an eccentric protoplanetary disk in a young binary system would further constrain planet formation theories.

scholarly journals Excitation of Gravity-Mode Pulsations in DA & DB White Dwarfs

2000 ◽  
Vol 176 ◽  
pp. 508-513 ◽  
Author(s):  
Yanqin Wu
Keyword(s):  
White Dwarfs ◽  
Energy Transport ◽  
Convective Motion ◽  
Convective Envelope ◽  
Dynamical Interaction ◽  
Pulsating Stars ◽  
Mode Excitation ◽  
Turbulent Damping ◽  
Gravity Mode ◽  
Radiative Damping

AbstractOscillations in white dwarfs of hydrogen or helium envelopes are believed to be excited close to the surface, where convective energy transport dominates the stellar luminosity. The convective motion in these stars is fast and can respond instantaneously to the pulsation state. In this limit, we find the convective envelope to be the seat of mode excitation because it acts as an insulating blanket with respect to the perturbed flux that enters it from below. This retaining of the flux leads to driving. Driving exceeds radiative damping providedωτc≥ 1, whereωis the radian frequency of the mode andτc≈ 4τthwith τthbeing the thermal time constant evaluated at the base of the convective envelope. We follow Brickhill (1991) in naming this mechanism as ‘convective driving’. We also studied the dynamical interaction between turbulent convection and pulsation. In the limit of fast convection, turbulent damping inside the convective region is negligible, while that coming from the overshoot region is more significant. I discuss the application of ‘convective driving’ in other types of pulsating stars.

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