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Adrian J. Barker - One of the best experts on this subject based on the ideXlab platform.
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Layered semi-convection and tides in giant Planet Interiors - II. Tidal dissipation
Astronomy & Astrophysics, 2019Co-Authors: Q. André, Stephane Mathis, Adrian J. BarkerAbstract:Context. Recent Juno observations have suggested that the heavy elements in Jupiter could be diluted throughout a large fraction of its gaseous envelope, providing a stabilising compositional gradient over an extended region of the Planet. This could trigger layered semi-convection, which, in the context of giant Planets more generally, may explain Saturn’s luminosity excess and play a role in causing the abnormally large radii of some hot Jupiters. In giant Planet Interiors, it could take the form of density staircases, which are convective layers separated by thin stably stratified interfaces. In addition, the efficiency of tidal dissipation is known to depend strongly on the Planetary internal structure. Aims. We aim to study the resulting tidal dissipation when internal waves are excited in a region of layered semi-convection by tidal gravitational forcing due to other bodies (such as moons in giant Planet systems, or stars in hot Jupiter systems). Methods. We adopt a local Cartesian model with a background layered density profile subjected to an imposed tidal forcing, and we compute the viscous and thermal dissipation rates numerically. We consider two sets of boundary conditions in the vertical direction: periodic boundaries and impenetrable, stress-free boundaries, with periodic conditions in the horizontal directions in each case. These models are appropriate for studying the forcing of short-wavelength tidal waves in part of a region of layered semi-convection, and in an extended envelope containing layered semi-convection, respectively. Results. We find that the rates of tidal dissipation can be enhanced in a region of layered semi-convection compared to a uniformly convective medium, where the latter corresponds with the usual assumption adopted in giant Planet Interior models. In particular, a region of layered semi-convection possesses a richer set of resonances, allowing enhanced dissipation for a wider range of tidal frequencies. The details of these results significantly depend on the structural properties of the layered semi-convective regions. Conclusions. Layered semi-convection could contribute towards explaining the high tidal dissipation rates observed in Jupiter and Saturn, which have not yet been fully explained by theory. Further work is required to explore the efficiency of this mechanism in global models.
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Layered semi-convection and tides in giant Planet Interiors
Astronomy and Astrophysics - A&A, 2019Co-Authors: Q. André, Stephane Mathis, Adrian J. BarkerAbstract:Context. Recent Juno observations have suggested that the heavy elements in Jupiter could be diluted throughout a large fraction of its gaseous envelope, providing a stabilising compositional gradient over an extended region of the Planet. This could trigger layered semi-convection, which, in the context of giant Planets more generally, may explain Saturn’s luminosity excess and play a role in causing the abnormally large radii of some hot Jupiters. In giant Planet Interiors, it could take the form of density staircases, which are convective layers separated by thin stably stratified interfaces. In addition, the efficiency of tidal dissipation is known to depend strongly on the Planetary internal structure.Aims. We aim to study the resulting tidal dissipation when internal waves are excited in a region of layered semi-convection by tidal gravitational forcing due to other bodies (such as moons in giant Planet systems, or stars in hot Jupiter systems).Methods. We adopt a local Cartesian model with a background layered density profile subjected to an imposed tidal forcing, and we compute the viscous and thermal dissipation rates numerically. We consider two sets of boundary conditions in the vertical direction: periodic boundaries and impenetrable, stress-free boundaries, with periodic conditions in the horizontal directions in each case. These models are appropriate for studying the forcing of short-wavelength tidal waves in part of a region of layered semi-convection, and in an extended envelope containing layered semi-convection, respectively.Results. We find that the rates of tidal dissipation can be enhanced in a region of layered semi-convection compared to a uniformly convective medium, where the latter corresponds with the usual assumption adopted in giant Planet Interior models. In particular, a region of layered semi-convection possesses a richer set of resonances, allowing enhanced dissipation for a wider range of tidal frequencies. The details of these results significantly depend on the structural properties of the layered semi-convective regions.Conclusions. Layered semi-convection could contribute towards explaining the high tidal dissipation rates observed in Jupiter and Saturn, which have not yet been fully explained by theory. Further work is required to explore the efficiency of this mechanism in global models.
Q. André - One of the best experts on this subject based on the ideXlab platform.
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Layered semi-convection and tides in giant Planet Interiors - II. Tidal dissipation
Astronomy & Astrophysics, 2019Co-Authors: Q. André, Stephane Mathis, Adrian J. BarkerAbstract:Context. Recent Juno observations have suggested that the heavy elements in Jupiter could be diluted throughout a large fraction of its gaseous envelope, providing a stabilising compositional gradient over an extended region of the Planet. This could trigger layered semi-convection, which, in the context of giant Planets more generally, may explain Saturn’s luminosity excess and play a role in causing the abnormally large radii of some hot Jupiters. In giant Planet Interiors, it could take the form of density staircases, which are convective layers separated by thin stably stratified interfaces. In addition, the efficiency of tidal dissipation is known to depend strongly on the Planetary internal structure. Aims. We aim to study the resulting tidal dissipation when internal waves are excited in a region of layered semi-convection by tidal gravitational forcing due to other bodies (such as moons in giant Planet systems, or stars in hot Jupiter systems). Methods. We adopt a local Cartesian model with a background layered density profile subjected to an imposed tidal forcing, and we compute the viscous and thermal dissipation rates numerically. We consider two sets of boundary conditions in the vertical direction: periodic boundaries and impenetrable, stress-free boundaries, with periodic conditions in the horizontal directions in each case. These models are appropriate for studying the forcing of short-wavelength tidal waves in part of a region of layered semi-convection, and in an extended envelope containing layered semi-convection, respectively. Results. We find that the rates of tidal dissipation can be enhanced in a region of layered semi-convection compared to a uniformly convective medium, where the latter corresponds with the usual assumption adopted in giant Planet Interior models. In particular, a region of layered semi-convection possesses a richer set of resonances, allowing enhanced dissipation for a wider range of tidal frequencies. The details of these results significantly depend on the structural properties of the layered semi-convective regions. Conclusions. Layered semi-convection could contribute towards explaining the high tidal dissipation rates observed in Jupiter and Saturn, which have not yet been fully explained by theory. Further work is required to explore the efficiency of this mechanism in global models.
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Layered semi-convection and tides in giant Planet Interiors
Astronomy and Astrophysics - A&A, 2019Co-Authors: Q. André, Stephane Mathis, Adrian J. BarkerAbstract:Context. Recent Juno observations have suggested that the heavy elements in Jupiter could be diluted throughout a large fraction of its gaseous envelope, providing a stabilising compositional gradient over an extended region of the Planet. This could trigger layered semi-convection, which, in the context of giant Planets more generally, may explain Saturn’s luminosity excess and play a role in causing the abnormally large radii of some hot Jupiters. In giant Planet Interiors, it could take the form of density staircases, which are convective layers separated by thin stably stratified interfaces. In addition, the efficiency of tidal dissipation is known to depend strongly on the Planetary internal structure.Aims. We aim to study the resulting tidal dissipation when internal waves are excited in a region of layered semi-convection by tidal gravitational forcing due to other bodies (such as moons in giant Planet systems, or stars in hot Jupiter systems).Methods. We adopt a local Cartesian model with a background layered density profile subjected to an imposed tidal forcing, and we compute the viscous and thermal dissipation rates numerically. We consider two sets of boundary conditions in the vertical direction: periodic boundaries and impenetrable, stress-free boundaries, with periodic conditions in the horizontal directions in each case. These models are appropriate for studying the forcing of short-wavelength tidal waves in part of a region of layered semi-convection, and in an extended envelope containing layered semi-convection, respectively.Results. We find that the rates of tidal dissipation can be enhanced in a region of layered semi-convection compared to a uniformly convective medium, where the latter corresponds with the usual assumption adopted in giant Planet Interior models. In particular, a region of layered semi-convection possesses a richer set of resonances, allowing enhanced dissipation for a wider range of tidal frequencies. The details of these results significantly depend on the structural properties of the layered semi-convective regions.Conclusions. Layered semi-convection could contribute towards explaining the high tidal dissipation rates observed in Jupiter and Saturn, which have not yet been fully explained by theory. Further work is required to explore the efficiency of this mechanism in global models.
Stephane Mathis - One of the best experts on this subject based on the ideXlab platform.
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Layered semi-convection and tides in giant Planet Interiors - II. Tidal dissipation
Astronomy & Astrophysics, 2019Co-Authors: Q. André, Stephane Mathis, Adrian J. BarkerAbstract:Context. Recent Juno observations have suggested that the heavy elements in Jupiter could be diluted throughout a large fraction of its gaseous envelope, providing a stabilising compositional gradient over an extended region of the Planet. This could trigger layered semi-convection, which, in the context of giant Planets more generally, may explain Saturn’s luminosity excess and play a role in causing the abnormally large radii of some hot Jupiters. In giant Planet Interiors, it could take the form of density staircases, which are convective layers separated by thin stably stratified interfaces. In addition, the efficiency of tidal dissipation is known to depend strongly on the Planetary internal structure. Aims. We aim to study the resulting tidal dissipation when internal waves are excited in a region of layered semi-convection by tidal gravitational forcing due to other bodies (such as moons in giant Planet systems, or stars in hot Jupiter systems). Methods. We adopt a local Cartesian model with a background layered density profile subjected to an imposed tidal forcing, and we compute the viscous and thermal dissipation rates numerically. We consider two sets of boundary conditions in the vertical direction: periodic boundaries and impenetrable, stress-free boundaries, with periodic conditions in the horizontal directions in each case. These models are appropriate for studying the forcing of short-wavelength tidal waves in part of a region of layered semi-convection, and in an extended envelope containing layered semi-convection, respectively. Results. We find that the rates of tidal dissipation can be enhanced in a region of layered semi-convection compared to a uniformly convective medium, where the latter corresponds with the usual assumption adopted in giant Planet Interior models. In particular, a region of layered semi-convection possesses a richer set of resonances, allowing enhanced dissipation for a wider range of tidal frequencies. The details of these results significantly depend on the structural properties of the layered semi-convective regions. Conclusions. Layered semi-convection could contribute towards explaining the high tidal dissipation rates observed in Jupiter and Saturn, which have not yet been fully explained by theory. Further work is required to explore the efficiency of this mechanism in global models.
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Layered semi-convection and tides in giant Planet Interiors
Astronomy and Astrophysics - A&A, 2019Co-Authors: Q. André, Stephane Mathis, Adrian J. BarkerAbstract:Context. Recent Juno observations have suggested that the heavy elements in Jupiter could be diluted throughout a large fraction of its gaseous envelope, providing a stabilising compositional gradient over an extended region of the Planet. This could trigger layered semi-convection, which, in the context of giant Planets more generally, may explain Saturn’s luminosity excess and play a role in causing the abnormally large radii of some hot Jupiters. In giant Planet Interiors, it could take the form of density staircases, which are convective layers separated by thin stably stratified interfaces. In addition, the efficiency of tidal dissipation is known to depend strongly on the Planetary internal structure.Aims. We aim to study the resulting tidal dissipation when internal waves are excited in a region of layered semi-convection by tidal gravitational forcing due to other bodies (such as moons in giant Planet systems, or stars in hot Jupiter systems).Methods. We adopt a local Cartesian model with a background layered density profile subjected to an imposed tidal forcing, and we compute the viscous and thermal dissipation rates numerically. We consider two sets of boundary conditions in the vertical direction: periodic boundaries and impenetrable, stress-free boundaries, with periodic conditions in the horizontal directions in each case. These models are appropriate for studying the forcing of short-wavelength tidal waves in part of a region of layered semi-convection, and in an extended envelope containing layered semi-convection, respectively.Results. We find that the rates of tidal dissipation can be enhanced in a region of layered semi-convection compared to a uniformly convective medium, where the latter corresponds with the usual assumption adopted in giant Planet Interior models. In particular, a region of layered semi-convection possesses a richer set of resonances, allowing enhanced dissipation for a wider range of tidal frequencies. The details of these results significantly depend on the structural properties of the layered semi-convective regions.Conclusions. Layered semi-convection could contribute towards explaining the high tidal dissipation rates observed in Jupiter and Saturn, which have not yet been fully explained by theory. Further work is required to explore the efficiency of this mechanism in global models.
Sara Seager - One of the best experts on this subject based on the ideXlab platform.
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Three Possible Origins for the Gas Layer on GJ 1214b
The Astrophysical Journal, 2010Co-Authors: Leslie A. Rogers, Sara SeagerAbstract:We present an analysis of the bulk composition of the MEarth transiting super Earth exoPlanet GJ 1214b using Planet Interior structure models. We consider three possible origins for the gas layer on GJ 1214b: direct accretion of gas from the protoPlanetary nebula, sublimation of ices, and outgassing from rocky material. Armed only with measurements of the Planet mass (M_p=6.55+/-0.98 M_{earth}), radius (R_p=2.678+/-0.13 R_{earth}), and stellar irradiation level, our main conclusion is that we cannot infer a unique composition. A diverse range of Planet Interiors fits the measured Planet properties. Nonetheless, GJ 1214b's relatively low average density (rho_p=1870+/-400 kg m^{-3}) means that it almost certainly has a significant gas component. Our second major conclusion is that under most conditions we consider GJ 1214b would not have liquid water. Even if the outer envelope is predominantly sublimated water ice, the envelope will likely consist of a super-fluid layer sandwiched between vapor above and plasma (electrically conductive fluid) below at greater depths. In our models, a low intrinsic Planet luminosity (
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A Framework for Quantifying the Degeneracies of ExoPlanet Interior Compositions
The Astrophysical Journal, 2010Co-Authors: Leslie A. Rogers, Sara SeagerAbstract:Several transiting super-Earths are expected to be discovered in the coming few years. While tools to model the Interior structure of transiting Planets exist, inferences about the composition are fraught with ambiguities. We present a framework to quantify how much we can robustly infer about super-Earth and Neptune-size exoPlanet Interiors from radius and mass measurements. We introduce quaternary diagrams to illustrate the range of possible Interior compositions for Planets with four layers (iron core, silicate mantles, water layers, and H/He envelopes). We apply our model to CoRoT-7b, GJ 436b, and HAT-P-11b. Interpretation of Planets with H/He envelopes is limited by the model uncertainty in the Interior temperature, while for CoRoT-7b observational uncertainties dominate. We further find that our Planet Interior model sharpens the observational constraints on CoRoT-7b's mass and radius, assuming the Planet does not contain significant amounts of water or gas. We show that the strength of the limits that can be placed on a super-Earth's composition depends on the Planet's density; for similar observational uncertainties, high-density super-Mercuries allow the tightest composition constraints. Finally, we describe how techniques from Bayesian statistics can be used to take into account in a formal way the combined contributions of both theoretical and observational uncertainties to ambiguities in a Planet's Interior composition. On the whole, with only a mass and radius measurement an exact Interior composition cannot be inferred for an exoPlanet because the problem is highly underconstrained. Detailed quantitative ranges of plausible compositions, however, can be found.
Dimitar Sasselov - One of the best experts on this subject based on the ideXlab platform.
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THE EFFECT OF TEMPERATURE EVOLUTION ON THE Interior STRUCTURE OF H2O-RICH PlanetS
The Astrophysical Journal, 2014Co-Authors: Li Zeng, Dimitar SasselovAbstract:For most Planets in the range of radii from 1 to 4 R ⊕, water is a major component of the Interior composition. At high pressure H2O can be solid, but for larger Planets, like Neptune, the temperature can be too high for this. Mass and age play a role in determining the transition between solid and fluid (and mixed) water-rich super-Earth. We use the latest high-pressure and ultra-high-pressure phase diagrams of H2O, and by comparing them with the Interior adiabats of various Planet models, the temperature evolution of the Planet Interior is shown, especially for the state of H2O. It turns out that the bulk of H2O in a Planet's Interior may exist in various states such as plasma, superionic, ionic, Ice VII, Ice X, etc., depending on the size, age, and cooling rate of the Planet. Different regions of the mass-radius phase space are also identified to correspond to different Planet structures. In general, super-Earth-size Planets (isolated or without significant parent star irradiation effects) older than about 3 Gyr would be mostly solid.