The thermodynamics of collapsing molecular cloud cores using smoothed particle hydrodynamics with radiative transfer

Whitehouse, Stuart C.; Bate, Matthew R.

doi:10.1111/j.1365-2966.2005.09950.x

Cited by 174 publications

(222 citation statements)

References 36 publications

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“…We can clearly see that for densities below 10 −10 g cm −3 , the Tea13 behaves very much like an ideal gas with γ = 5/3. The EOS used by Whitehouse & Bate (2006) seems to operate in a very similar manner, while the simulations of MI00 and SWBG07 follow our thermal track much more closely. One of the main differences between the various EOS used by the different studies is the treatment of the different spin isomers of the H 2 molecule in the low-to-moderate temperature regime.…”

Section: Atomic Gasmentioning

confidence: 86%

Simulations of protostellar collapse using multigroup radiation hydrodynamics

Vaytet

Chabrier

Audit

et al. 2013

A&A

111

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Context. Star formation begins with the gravitational collapse of a dense core inside a molecular cloud. As the collapse progresses, the centre of the core begins to heat up as it becomes optically thick. The temperature and density in the centre eventually reach high enough values where fusion reactions can ignite, and the protostar is born. This sequence of events entails many physical processes, of which radiative transfer is of paramount importance. Simulated collapsing cores without radiative transfer rapidly become thermally supported before reaching high enough temperatures and densities, preventing the formation of stars. Aims. Many simulations of protostellar collapse make use of a grey treatment of radiative transfer coupled to the hydrodynamics. However, interstellar gas and dust opacities present large variations as a function of frequency, which can potentially be overlooked by grey models and lead to significantly different results. In this paper, we follow up on a previous paper on the collapse and formation of Larson's first core using multigroup radiation hydrodynamics (Paper I) by extending the calculations to the second phase of the collapse and the formation of Larson's second core. Methods. We have made the use of a non-ideal gas equation of state as well as an extensive set of spectral opacities in a spherically symmetric fully implicit Godunov code to model all the phases of the collapse of a 0.1, 1, and 10 M cloud cores. Results. We find that, for an identical central density, there are only small differences between the grey and multigroup simulations. The first core accretion shock remains supercritical while the shock at the second core border is found to be strongly subcritical with all the accreted energy being transfered to the core. The size of the first core was found to vary somewhat in the different simulations (more unstable clouds form smaller first cores) while the size, mass, and temperature of the second cores are independent of initial cloud mass, size, and temperature. Conclusions. Our simulations support the idea of a standard (universal) initial second core size of ∼3 × 10 −3 AU and mass ∼1.4 × 10 −3 M . The grey approximation for radiative transfer appears to perform well in one-dimensional simulations of protostellar collapse, most probably because of the high optical thickness of the majority of the protostar-envelope system. A simple estimate of the characteristic timescale of the second core suggests that the effects of using multigroup radiative transfer may be more important in the long-term evolution of the protostar.

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Section: Atomic Gasmentioning

confidence: 86%

Simulations of protostellar collapse using multigroup radiation hydrodynamics

Vaytet

Chabrier

Audit

et al. 2013

A&A

111

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“…Testing the numerical method for radiative shock calculations is a last important step that every code attempting to integrate RHD equations should perform (Hayes & Norman 2003;Whitehouse & Bate 2006;González et al 2007). Following the Ensman (1994) initial conditions, we tested our routine for sub-and super-critical radiative shocks.…”

Section: D Full Rhd Tests: Radiative Shocksmentioning

confidence: 99%

“…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

159

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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“…The five studies compared were the works of Masunaga & Inutsuka (2000), Whitehouse & Bate (2006), Stamatellos et al (2007), Tomida et al (2013), and Vaytet et al (2013). The argument was that works that made use of equilibrium OPR resembled ones that assume nonequilibrium OPR and vice-versa.…”

Section: Confusion In Other Studiesmentioning

confidence: 99%

“…Tomida et al (2013) use the non-equilibrium fixed 3:1 EOS of the present paper, and consequently shows a thermal evolution that strongly resembles run 1 (and run 4 even more). Whitehouse & Bate (2006) say that they use the model of Black & Bodenheimer (1975), which claims that equilibrium is assumed at all temperatures, yet the thermal path taken by their collapsing cloud echoes the nonequilibrium track. As discussed in Sect.…”

Section: Confusion In Other Studiesmentioning

confidence: 99%

On the role of the H₂ortho:para ratio in gravitational collapse during star formation

Vaytet

Tomida

Chabrier

2014

A&A

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Context. Hydrogen molecules (H 2 ) come in two forms, ortho-and para-hydrogen, corresponding to the two different spin configurations of the two hydrogen atoms. The relative abundances of the two flavours in the interstellar medium are still very uncertain, and this abundance ratio has a significant impact on the thermal properties of the gas. In the context of star formation, theoretical studies have recently adopted two different strategies when considering the ortho:para ratio (OPR) of H 2 molecules. The first considers the OPR to be frozen at 3:1, while the second assumes that the species are in thermal equilibrium at all temperatures. Aims. As the OPR potentially affects the protostellar cores that form as a result of the gravitational collapse of a dense molecular cloud, the aim of this paper is to quantify precisely what role the choice of OPR plays in the properties and evolution of the cores. Methods. We used two different ideal gas equations of state for a hydrogen and helium mix in a radiation hydrodynamics code to simulate the collapse of a dense cloud and the formation of the first and second Larson cores. The first equation of state uses a fixed OPR of 3:1, and the second assumes thermal equilibrium. Results. The OPR was found to markedly affect the evolution of the first core. Systems in simulations using an equilibrium ratio collapse faster at early times and show noticeable oscillations around hydrostatic equilibrium, to the point where the core expands for a short time right after its formation, before resuming its contraction. In the case of a fixed 3:1 OPR, the core's evolution is a lot smoother. The OPR was, however, found to have little impact on the size, mass, and radius of the two Larson cores. Conclusions. It is not clear from observational or theoretical studies of OPR in molecular clouds which OPR should be used in the context of star formation. Our simulations show that if one is solely interested in the final properties of the cores when they are formed, it does not matter which OPR is used. On the other hand, if one's focus lies primarily on the evolution of the first core, the choice of OPR becomes important.

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The thermodynamics of collapsing molecular cloud cores using smoothed particle hydrodynamics with radiative transfer

Cited by 174 publications

References 36 publications

Simulations of protostellar collapse using multigroup radiation hydrodynamics

Simulations of protostellar collapse using multigroup radiation hydrodynamics

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

On the role of the H₂ortho:para ratio in gravitational collapse during star formation

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The thermodynamics of collapsing molecular cloud cores using smoothed particle hydrodynamics with radiative transfer

Cited by 174 publications

References 36 publications

Simulations of protostellar collapse using multigroup radiation hydrodynamics

Simulations of protostellar collapse using multigroup radiation hydrodynamics

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

On the role of the H2ortho:para ratio in gravitational collapse during star formation

Contact Info

Product

Resources

About

On the role of the H₂ortho:para ratio in gravitational collapse during star formation