Radiative transfer and the energy equation in SPH simulations of star formation

Stamatellos, Dimitris; Whitworth, Anthony Peter; Bisbas, Thomas G.; Goodwin, S. P.

doi:10.1051/0004-6361:20077373

Cited by 169 publications

(333 citation statements)

References 43 publications

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“…Mihalas & Mihalas 1984;Lowrie et al 2001;Mihalas & Auer 2001;Krumholz et al 2007b). Radiation hydrodynamics (RHD) methods have been developed in grid-based codes (Stone & Norman 1992;Hayes & Norman 2003;Krumholz et al 2007a;Kuiper et al 2010;Sekora & Stone 2010;Tomida et al 2010) and also in smoothed particles hydrodynamics (SPH) codes (Boss et al 2000;Whitehouse & Bate 2006;Stamatellos et al 2007). Most of these studies use the popular flux-limited diffusion approximation (FLD, e.g.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…Some of these investigations have at least realized to follow the second collapse (forming the protostellar core), but either did not reach a quasi-static state for the stellar core, cf. Stamatellos et al (2007), Saigo et al (2008), or could follow the post-collapse evolution for only a short period of time (about 60 d, cf. Bate 1998).…”

Section: Introductionmentioning

confidence: 99%

Protostellar collapse of rotating cloud cores

Schönke

Tscharnuter

2011

A&A

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Aims. We investigate the influence of turbulent viscosity on the collapse of a rotating molecular cloud core with axial symmetry, in particular, on the first and second collapse phase, as well as the evolution of the second (protostellar) core during its first accretion period. By using extensive numerical calculations, we monitor the intricate interactions between the newly formed protostar and the surrounding accretion disk (the first core) in which the star is embedded. Methods. We use a grid-based radiation-hydrodynamics code with a spatial grid designed to meet the high resolution required to study the second core. The radiative transfer is treated in the flux-limited diffusion approximation. A slightly supercritical Bonnor-Ebert sphere of 1 M and uniform rotation according to a fixed centrifugal radius of 100 AU serves as the initial condition without exception. In a parameter study, we vary the β-viscosity driving the angular momentum transport. Results. Without viscosity (β = 0), a highly flattened accretion disk forms that fragments into several "cold" rings. For β = 10 −4 , a single "warm" ring forms that undergoes collapse due to hydrogen dissociation. For β = 10 −3 , ring formation is suppressed completely. The second collapse proceeds on the local thermal timescale, which is in contrast to the current view of a generally dynamical second collapse. During the first accretion period of the second core, the first core heats up globally and, as a consequence, a nearly spherical outflow occurs, destroying the structure of the former accretion disk completely. Finally, for β = 10 −2 , we see the classical dynamical second collapse and a shorter but more rapid accretion phase. The impact on the surrounding accretion disk is even more pronounced. We follow the resulting massive outflow up to several kyr after the second collapse, where the central parts (R < 0.7 AU) are now cut out and replaced with an appropriate inner boundary condition. Matter is found to turn back to the center at a radius of 500 AU after about 4 kyr and to reach the protostar again after approximately 7 kyr. The results suggest that the star formation process consists of short and rapid accretion phases (lasting on the order of 100 yr) between long and quiet outflow periods (lasting several kyr).

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“…Sink particles have radius rsink 0.2 au, corresponding to the smoothing length of an SPH particle with density equal to ρsink. The equation of state and the energy equation are treated with the radiative transfer approximation described by Stamatellos et al (2007) (hereafter SW07).…”

Section: Smoothed Particle Hydrodynamicsmentioning

confidence: 99%

Synthetic observations of protostellar multiple systems

Lomax

Whitworth

2018

Monthly Notices of the Royal Astronomical Society

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Observations of protostars are often compared with synthetic observations of models in order to infer the underlying physical properties of the protostars. The majority of these models have a single protostar, attended by a disc and an envelope. However, observational and numerical evidence suggests that a large fraction of protostars form as multiple systems. This means that fitting models of single protostars to observations may be inappropriate. We produce synthetic observations of protostellar multiple systems undergoing realistic, non-continuous accretion. These systems consist of multiple protostars with episodic luminosities, embedded self-consistently in discs and envelopes. We model the gas dynamics of these systems using smoothed particle hydrodynamics and we generate synthetic observations by post-processing the snapshots using the spamcart Monte Carlo radiative transfer code. We present simulation results of three model protostellar multiple systems. For each of these, we generate 4×10 4 synthetic spectra at different points in time and from different viewing angles. We propose a Bayesian method, using similar calculations to those presented here, but in greater numbers, to infer the physical properties of protostellar multiple systems from observations.

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Radiative transfer and the energy equation in SPH simulations of star formation

Cited by 169 publications

References 43 publications

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

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

Protostellar collapse of rotating cloud cores

Synthetic observations of protostellar multiple systems

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