A multigroup diffusion solver using pseudo transient continuation for a radiation-hydrodynamic code with patch-based AMR

Shestakov, A. I.; Offner, Stella S. R.

doi:10.1016/j.jcp.2007.09.019

Cited by 29 publications

(29 citation statements)

References 22 publications

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“…ORION includes (Klein 1999), radiative transfer (Howell & Greenough 2003;Krumholz et al 2007;Shestakov & Offner 2008;Rosen et al 2016), self-gravity (Truelove et al 1998), accreting sink particles (Truelove et al 1997;Krumholz et al 2004), a protostellar evolution model used to represent the sink particles as radiating protostars ), protostellar outflows (Cunningham et al 2011), and magnetic fields (Li Weingartner & Draine (2001) for their R v = 5.5 extinction curve (teal line) with black body weighted binned opacities (pink diamonds) over-plotted for ten frequency bins used in the simulations presented in this work.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

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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Section: Methodsmentioning

confidence: 99%

“…The implicit solve update is handled by the iterative process described in Shestakov & Offner (2008) that uses pseudo-transient continuation to reduce the number of iterations. Finally, we update the sink particle states with Equations (7)-(9) by computing their interactions with the fluid.…”

Section: Overall Algorithmmentioning

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 underlying physical idea is simple: in an optically thick environment like the dusty clouds in which stars form, radiation diffuses through the gas like heat, and the radiative flux F obeys Fick's Law: F = −c∇E/(3κρ), where E is the radiation energy density, ρ is the gas density, and κ is the specific opacity, with units of area divided by mass. This is the standard diffusion approximation, and it can be made either in a gray form by integrating E and F over all frequencies, or in a multi-group form in which one divides the spectrum into some number of intervals in frequency and computes a separate energy density and flux for each interval (Shestakov and Offner, 2008;Yorke and Sonnhalter, 2002).…”

Section: Numerical Methods For Non-ionizing Radiation Feedbackmentioning

confidence: 99%

“…One treats feedback from stars in this formulation simply by adding it as a source term or a boundary condition in the radiation energy equation. The resulting set of equations may be written using either a comoving (Boss and Myhill, 1992;Hayes et al, 2006;Stone et al, 1992;Tscharnuter, 1987;Whitehouse and Bate, 2004;Whitehouse et al, 2005) or a mixed-frame (Howell and Greenough, 2003;Krumholz et al, 2007b;Shestakov and Offner, 2008) formulation. The former approach is more suited to implementation in a code that is either Lagrangean, such as SPH, or based on van Leer advection (van Leer, 1977), but has the disadvantage that the equations are not explicitly conservative, and so the resulting codes cannot precisely conserve energy.…”

Section: Numerical Methods For Non-ionizing Radiation Feedbackmentioning

confidence: 99%

Numerical Star-Formation Studies— A Status Report

Klessen¹,

Krumholz²,

Heitsch³

2011

adv sci lett

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The formation of stars is a key process in astrophysics. Detailed knowledge of the physical mechanisms that govern stellar birth is a prerequisite for understanding the formation and evolution of our galactic home, the Milky Way. A theory of star formation is an essential part of any model for the origin of our solar system and of planets around other stars. Despite this pivotal importance, and despite many decades of research, our understanding of the processes that initiate and regulate star formation is still limited. Stars are born in cold interstellar clouds of molecular hydrogen gas. Star formation in these clouds is governed by the complex interplay between the gravitational attraction in the gas and agents such as turbulence, magnetic fields, radiation and thermal pressure that resist compression. The competition between these processes determines both the locations at which young stars form and how much mass they ultimately accrete. It plays out over many orders of magnitude in space and time, ranging from galactic to stellar scales. In addition, star formation is a highly stochastic process in which rare and hard-to-predict events, such as the formation of very massive stars and the resulting feedback, can play a dominant role in determining the evolution of a star-forming cloud. As a consequence of the wide range of scales and processes that control star formation, analytic models are usually restricted to highly idealized cases. These can yield insight, but the complexity of the problem means that they must be used in concert with large-scale numerical simulations. Here we summarize the state of modern star formation theory and review the recent advances in numerical simulation techniques.

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“…Some attempts have been presented in the literature (e.g. Shestakov & Offner 2008), but the computational cost remains too high nowadays compared to the grey model. implement compared to implicit methods that involve matrix inversions.…”

Section: Summary and Perspectivesmentioning

confidence: 99%

Radiation hydrodynamics with adaptive mesh refinement and application to prestellar core collapse

Commerçon

Teyssier²,

Audit³

et al. 2011

A&A

160

174

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Context. Radiative transfer has a strong impact on the collapse and the fragmentation of prestellar dense cores. Aims. We present the radiation-hydrodynamics (RHD) solver we designed for the RAMSES code. The method is designed for astrophysical purposes, and in particular for protostellar collapse. Methods. We present the solver, using the co-moving frame to evaluate the radiative quantities. We use the popular flux-limited diffusion approximation under the grey approximation (one group of photons). The solver is based on the second-order Godunov scheme of RAMSES for its hyperbolic part and on an implicit scheme for the radiation diffusion and the coupling between radiation and matter. Results. We report in detail our methodology to integrate the RHD solver into RAMSES. We successfully test the method in several conventional tests. For validation in 3D, we perform calculations of the collapse of an isolated 1 M prestellar dense core without rotation. We successfully compare the results with previous studies that used different models for radiation and hydrodynamics. Conclusions. We have developed a full radiation-hydrodynamics solver in the RAMSES code that handles adaptive mesh refinement grids. The method is a combination of an explicit scheme and an implicit scheme accurate to the second-order in space. Our method is well suited for star-formation purposes. Results of multidimensional dense-core-collapse calculations with rotation are presented in a companion paper.

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A multigroup diffusion solver using pseudo transient continuation for a radiation-hydrodynamic code with patch-based AMR

Cited by 29 publications

References 22 publications

An unstable truth: how massive stars get their mass

An unstable truth: how massive stars get their mass

Numerical Star-Formation Studies— A Status Report

Radiation hydrodynamics with adaptive mesh refinement and application to prestellar core collapse

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