The Planetary Accretion Shock: I. Framework for Radiation-hydrodynamical Simulations and First Results

Abstract

The key aspect determining the post-formation luminosity of gas giants has long been considered to be the energetics of the accretion shock at the planetary surface. We use 1D radiation-hydrodynamical simulations to study the radiative loss efficiency and to obtain post-shock temperatures and pressures and thus entropies. The efficiency is defined as the fraction of the total incoming energy flux which escapes the system (roughly the Hill sphere), taking into account the energy recycling which occurs ahead of the shock in a radiative precursor. We focus here on a constant equation of state to isolate the shock physics but use constant and tabulated opacities. While robust quantitative results will require a self-consistent treatment including hydrogen dissocation and ionization, the results show the correct qualitative behavior and can be understood semi-analytically. The shock is found to be isothermal and supercritical for a range of conditions relevant to core accretion (CA), with Mach numbers greater than ca. 3. Across the shock, the entropy decreases significantly, by a few entropy units (k_B/baryon). While nearly 100 percent of the incoming kinetic energy is converted to radiation locally, the efficiencies are found to be as low as roughly 40 percent, implying that a meaningful fraction of the total accretion energy is brought into the planet. For realistic parameter combinations in the CA scenario, a non-zero fraction of the luminosity always escapes the system. This luminosity could explain, at least in part, recent observations in the LkCa 15 and HD 100546 systems.

15 pages, 4 figures. Accepted for publication in ApJ

References in corpus (50)

• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• PLUTO: a Numerical Code for Computational Astrophysics
• Using FU Orionis Outbursts to Constrain Self-Regulated Protostellar Disk Models
• The Gemini Planet Imager: First Light
• A Giant Planet Candidate near a Young Brown Dwarf
• A probable giant planet imaged in the Beta Pictoris disk
• Rosseland and Planck Mean Opacities for Protoplanetary Discs
• On the Luminosity of Young Jupiters
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• The PLUTO Code for Adaptive Mesh Computations in Astrophysical Fluid Dynamics
• Spectral and Photometric Diagnostics of Giant Planet Formation Scenarios
• Imaging Extrasolar Giant Planets
• Models of the in situ formation of detected extrasolar giant planets
• Characterization of exoplanets from their formation I: Models of combined planet formation and evolution
• Accreting Protoplanets in the LkCa 15 Transition Disk
• Models of Jupiter's Growth Incorporating Thermal and Hydrodynamic Constraints
• Orbital Migration and Mass Accretion of Protoplanets in 3D Global Computations with Nested Grids
• Characterization of exoplanets from their formation II: The planetary mass-radius relationship
• Direct Imaging and Spectroscopy of a Planetary Mass Candidate Companion to a Young Solar Analog
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• The Gemini NICI Planet-Finding Campaign: The Frequency of Planets around Young Moving Group Stars
• Hydrodynamics of Embedded Planets' First Atmospheres. II. A Rapid Recycling of Atmospheric Gas
• Accreting Circumplanetary Disks: Observational Signatures
• Constraining the initial entropy of directly-detected exoplanets
• Observed luminosity spread in young clusters and Fu Ori stars: a unified picture
• A Statistical Analysis of SEEDS and Other High-Contrast Exoplanet Surveys: Massive Planets or Low-Mass Brown Dwarfs?
• Circumplanetary disk or circumplanetary envelope?
• Discovery of H-alpha Emission from the Close Companion Inside the Gap of Transitional Disk HD142527
• Gas accretion onto planetary cores: three-dimensional self-gravitating radiation hydrodynamical calculations
• Fast and accurate frequency-dependent radiation transport for hydrodynamics simulations in massive star formation
• The 3D Flow Field Around an Embedded Planet
• Luminosity of young Jupiters revisited. Massive cores make hot planets
• Thermal Structure and Radius Evolution of Irradiated Gas Giant Planets
• Three-Dimensional Radiation-Hydrodynamics Calculations of the Envelopes of Young Planets Embedded in Protoplanetary Disks
• Synthesizing Exoplanet Demographics: A Single Population of Long-Period Planetary Companions to M Dwarfs Consistent with Microlensing, Radial Velocity, and Direct Imaging Surveys
• Performance of the VLT Planet Finder SPHERE I. Photometry and astrometry precision with IRDIS and IFS in laboratory
• Simulations of protostellar collapse using multigroup radiation hydrodynamics. II. The second collapse
• Evolution of Gas Giant Entropy During Formation by Runaway Accretion
• Thermodynamics of Giant Planet Formation: Shocking Hot Surfaces on Circumplanetary Disks
• Mean gas opacity for circumstellar environments and equilibrium temperature degeneracy
• Physical and radiative properties of the first core accretion shock
• The reliability of approximate radiation transport methods for irradiated disk studies
• Accretion of gas onto gap-opening planets and circumplanetary flow structure in magnetized turbulent disks
• Possible Signatures of Magnetospheric Accretion onto Young Giant Planets
• The Optical Design of CHARIS: An Exoplanet IFS for the Subaru Telescope
• The influence of frequency-dependent radiative transfer on the structures of radiative shocks
• High contrast imaging at the LBT: the LEECH exoplanet imaging survey
• Search for exoplanets and brown dwarfs with VLBI
• Magnetic fields in gaps surrounding giant protoplanets

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