Hybrid characteristics: 3D radiative transfer for parallel adaptive mesh refinement hydrodynamics

Rijkhorst, E.-J.; Plewa, T.; Dubey, Anshu; Mellema, Garrelt

doi:10.1051/0004-6361:20053401

Cited by 111 publications

(139 citation statements)

References 31 publications

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“…Toon et al 1989;Marley & McKay 1999;Fortney et al 2006) or ray-tracing method (e.g. Rijkhorst et al 2006). Since MCRT tracks the random walk of a packet and its interactions, radiative transfer through complicated 3D geometries, inhomogeneous opacities, and highly multiple scattering regions can be modelled.…”

Section: Mcrt Modelling Frameworkmentioning

confidence: 99%

Dynamic mineral clouds on HD 189733b

Lee

Wood

Dobbs-Dixon

et al. 2017

A&A

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Context. As the 3D spatial properties of exoplanet atmospheres are being observed in increasing detail by current and new generations of telescopes, the modelling of the 3D scattering effects of cloud forming atmospheres with inhomogeneous opacity structures becomes increasingly important to interpret observational data. Aims. We model the scattering and emission properties of a simulated cloud forming, inhomogeneous opacity, hot Jupiter atmosphere of HD 189733b. We compare our results to available Hubble Space Telescope (HST) and Spitzer data and quantify the effects of 3D multiple scattering on observable properties of the atmosphere. We discuss potential observational properties of HD 189733b for the upcoming Transiting Exoplanet Survey Satellite (TESS) and CHaracterising ExOPlanet Satellite (CHEOPS) missions. Methods. We developed a Monte Carlo radiative transfer code and applied it to post-process output of our 3D radiative-hydrodynamic, cloud formation simulation of HD 189733b. We employed three variance reduction techniques, i.e. next event estimation, survival biasing, and composite emission biasing, to improve signal to noise of the output. For cloud particle scattering events, we constructed a log-normal area distribution from the 3D cloud formation radiative-hydrodynamic results, which is stochastically sampled in order to model the Rayleigh and Mie scattering behaviour of a mixture of grain sizes. Results. Stellar photon packets incident on the eastern dayside hemisphere show predominantly Rayleigh, single-scattering behaviour, while multiple scattering occurs on the western hemisphere. Combined scattered and thermal emitted light predictions are consistent with published HST and Spitzer secondary transit observations. Our model predictions are also consistent with geometric albedo constraints from optical wavelength ground-based polarimetry and HST B band measurements. We predict an apparent geometric albedo for HD 189733b of 0.205 and 0.229, in the TESS and CHEOPS photometric bands respectively. Conclusions. Modelling the 3D geometric scattering effects of clouds on observables of exoplanet atmospheres provides an important contribution to the attempt to determine the cloud properties of these objects. Comparisons between TESS and CHEOPS photometry may provide qualitative information on the cloud properties of nearby hot Jupiter exoplanets.

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Section: Mcrt Modelling Frameworkmentioning

confidence: 99%

Dynamic mineral clouds on HD 189733b

Lee

Wood

Dobbs-Dixon

et al. 2017

A&A

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“…It makes use of the paramesh library to solve the fluid equations on an adaptive Eulerian grid (Olson et al 1999;MacNeice et al 2000). The code has been expanded to include Lagrangian sink particles (Banerjee et al 2009; Federrath et al 2010), radiative heating and ionization feedback (Rijkhorst et al 2006;Peters et al 2010a), and selfconsistent protostellar evolution (Klassen et al 2012b). …”

Section: Numerical Simulationsmentioning

confidence: 99%

Filamentary flow and magnetic geometry in evolving cluster-forming molecular cloud clumps

Klassen

Pudritz

Kirk

2016

Mon. Not. R. Astron. Soc.

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We present an analysis of the relationship between the orientation of magnetic fields and filaments that form in 3D magnetohydrodynamic simulations of cluster-forming, turbulent molecular cloud clumps. We examine simulated cloud clumps with size scales of L ∼ 2-4 pc and densities of n ∼ 400-1000 cm −3 with Alfvén Mach numbers near unity. We simulated two cloud clumps of different masses, one in virial equilibrium, the other strongly gravitationally bound, but with the same initial turbulent velocity field and similar mass-to-flux ratio. We apply various techniques to analyze the filamentary and magnetic structure of the resulting cloud, including the DisPerSE filamentfinding algorithm in 3D. The largest structure that forms is a 1-2 parsec-long filament, with smaller connecting sub-filaments. We find that our simulated clouds, wherein magnetic forces and turbulence are comparable, coherent orientation of the magnetic field depends on the virial parameter. Subvirial clumps undergo strong gravitational collapse and magnetic field lines are dragged with the accretion flow. We see evidence of filament-aligned flow and accretion flow onto the filament in the subvirial cloud. Magnetic fields oriented more parallel in the subvirial cloud and more perpendicular in the denser, marginally bound cloud. Radiative feedback from a 16 M star forming in a cluster in one of our simulations ultimately results in the destruction of the main filament, the formation of an H ii region, and the sweeping up of magnetic fields within an expanding shell at the edges of the H ii region.

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“…The multi-frequency treatment is ideal for stars since they have color temperatures much higher than the absorbing medium. The raytracer employed in Klassen et al (2014) models only single frequency irradiation and uses hybrid characteristics, which is a combination of long characteristics within individual grids and short characteristics between grids (i.e., in which only neighboring grid cells are used to interpolate incoming intensities; Rijkhorst et al (2006)). The method of short characteristics is typically faster but more diffusive than long characteristics.…”

Section: Introductionmentioning

confidence: 99%

An unstable truth: how massive stars get their mass

Rosen¹,

Krumholz²,

McKee³

et al. 2016

Mon. Not. R. Astron. Soc.

141

188

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The pressure exerted by massive stars' radiation fields is an important mechanism regulating their formation. Detailed simulation of massive star formation therefore requires an accurate treatment of radiation. However, all published simulations have either used a diffusion approximation of limited validity; have only been able to simulate a single star fixed in space, thereby suppressing potentially-important instabilities; or did not provide adequate resolution at locations where instabilities may develop. To remedy this we have developed a new, highly accurate radiation algorithm that properly treats the absorption of the direct radiation field from stars and the re-emission and processing by interstellar dust. We use our new tool to perform three-dimensional radiation-hydrodynamic simulations of the collapse of massive pre-stellar cores with laminar and turbulent initial conditions and properly resolve regions where we expect instabilities to grow. We find that mass is channeled to the stellar system via gravitational and Rayleigh-Taylor (RT) instabilities, in agreement with previous results using stars capable of moving, but in disagreement with methods where the star is held fixed or with simulations that do not adequately resolve the development of RT instabilities. For laminar initial conditions, proper treatment of the direct radiation field produces later onset of instability, but does not suppress it entirely provided the edges of radiation-dominated bubbles are adequately resolved. Instabilities arise immediately for turbulent pre-stellar cores because the initial turbulence seeds the instabilities. Our results suggest that RT features are significant and should be present around accreting massive stars throughout their formation.

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Hybrid characteristics: 3D radiative transfer for parallel adaptive mesh refinement hydrodynamics

Cited by 111 publications

References 31 publications

Dynamic mineral clouds on HD 189733b

Dynamic mineral clouds on HD 189733b

Filamentary flow and magnetic geometry in evolving cluster-forming molecular cloud clumps

An unstable truth: how massive stars get their mass

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