SOC program for dust continuum radiative transfer

Juvela, M.

doi:10.1051/0004-6361/201834354

Cited by 35 publications

(28 citation statements)

References 51 publications

(67 reference statements)

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“…The radiative transfer calculations are made with the SOC code (Juvela 2019), which has been tested against other codes in the TRUST 15 benchmark project (Baes et al 2016;Gordon et al 2017). SOC is able to treat also stochastically heated grains (Camps et al 2015), but, to speed up the calculations, all grains are here assumed to be in thermal equilibrium with the radiation field.…”

Section: Appendixmentioning

confidence: 99%

The Origin of Massive Stars: The Inertial-inflow Model

Padoan

Pan²,

Juvela³

et al. 2020

ApJ

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134

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We address the problem of the origin of massive stars, namely the origin, path and timescale of the mass flows that create them. Based on extensive numerical simulations, we propose a scenario where massive stars are assembled by large-scale, converging, inertial flows that naturally occur in supersonic turbulence. We refer to this scenario of massive-star formation as the Inertial-Inflow Model. This model stems directly from the idea that the mass distribution of stars is primarily the result of turbulent fragmentation. Under this hypothesis, the statistical properties of the turbulence determine the formation timescale and mass of prestellar cores, posing definite constraints on the formation mechanism of massive stars. We quantify such constraints by the analysis of a simulation of supernova-driven turbulence in a 250-pc region of the interstellar medium, describing the formation of hundreds of massive stars over a time of approximately 30 Myr. Due to the large size of our statistical sample, we can say with full confidence that massive stars in general do not form from the collapse of massive cores, nor from competitive accretion, as both models are incompatible with the numerical results. We also compute synthetic continuum observables in Herschel and ALMA bands. We find that, depending on the distance of the observed regions, estimates of core mass based on commonlyused methods may exceed the actual core masses by up to two orders of magnitude, and that there is essentially no correlation between estimated and real core masses.

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Section: Appendixmentioning

confidence: 99%

The Origin of Massive Stars: The Inertial-inflow Model

Padoan

Pan²,

Juvela³

et al. 2020

ApJ

Self Cite

134

124

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“…SOC is a 3D Monte Carlo radiative transfer code, parallelised using OpenCL libraries (Juvela 2019). It computes dust emission and scattering.…”

Section: Radiative Transfer Code : Socmentioning

confidence: 99%

Dust evolution across the Horsehead nebula

Schirmer

Abergel

Verstraete

et al. 2020

A&A

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Context. Micro-physical processes on interstellar dust surfaces are tightly connected to dust properties (i.e. dust composition, size, and shape) and play a key role in numerous phenomena in the interstellar medium (ISM). The large disparity in physical conditions (i.e. density and gas temperature) in the ISM triggers an evolution of dust properties. The analysis of how dust evolves with the physical conditions is a stepping stone towards a more thorough understanding of interstellar dust. Aims. We highlight dust evolution in the Horsehead nebula photon-dominated region. Methods. We used Spitzer/IRAC (3.6, 4.5, 5.8 and 8 μm) and Spitzer/MIPS (24 μm) together with Herschel/PACS (70 and 160 μm) and Herschel/SPIRE (250, 350 and 500 μm) to map the spatial distribution of dust in the Horsehead nebula over the entire emission spectral range. We modelled dust emission and scattering using the THEMIS interstellar dust model together with the 3D radiative transfer code SOC. Results. We find that the nano-grain dust-to-gas ratio in the irradiated outer part of the Horsehead is 6–10 times lower than in the diffuse ISM. The minimum size of these grains is 2–2.25 times larger than in the diffuse ISM, and the power-law exponent of their size distribution is 1.1–1.4 times lower than in the diffuse ISM. In the denser part of the Horsehead nebula, it is necessary to use evolved grains (i.e. aggregates, with or without an ice mantle). Conclusions. It is not possible to explain the observations using grains from the diffuse medium. We therefore propose the following scenario to explain our results. In the outer part of the Horsehead nebula, all the nano-grain have not yet had time to re-form completely through photo-fragmentation of aggregates and the smallest of the nano-grain that are sensitive to the radiation field are photo-destroyed. In the inner part of the Horsehead nebula, grains most likely consist of multi-compositional mantled aggregates.

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“…The dust opacity model was the same as that used above. The calculations were done using the dust continuum radiative transfer program described in Juvela (2019). The isotropic field was set equal to 30 times the Mathis et al (1983) field, and the luminosity of point source (modeled as a 10,000 K blackbody) was selected so that its contribution to the radiation field at the cloud center was equal to that of the isotropic background.…”

Section: Appendix B Dust Temperature Distributionmentioning

confidence: 99%

Efficient Methanol Production on the Dark Side of a Prestellar Core

Harju

Pineda

Vasyunin

et al. 2020

ApJ

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We present Atacama Large Millimeter/submillimeter Array maps of the starless molecular cloud core Ophiuchus/ H-MM1 in the lines of deuterated ammonia (ortho-NH D 2), methanol (CH OH 3), and sulfur monoxide (SO). The dense core is seen in NH D 2 emission, whereas the CH OH 3 and SO distributions form a halo surrounding the core. Because methanol is formed on grain surfaces, its emission highlights regions where desorption from grains is particularly efficient. Methanol and sulfur monoxide are most abundant in a narrow zone that follows the eastern side of the core. This side is sheltered from the stronger external radiation field coming from the west. We show that photodissociation on the illuminated side can give rise to an asymmetric methanol distribution but that the stark contrast observed in H-MM1 is hard to explain without assuming enhanced desorption on the shaded side. The region of the brightest emission has a wavy structure that rolls up at one end. This is the signature of Kelvin-Helmholtz instability occurring in sheared flows. We suggest that in this zone, methanol and sulfur are released as a result of grain-grain collisions induced by shear vorticity.

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SOC program for dust continuum radiative transfer

Cited by 35 publications

References 51 publications

The Origin of Massive Stars: The Inertial-inflow Model

The Origin of Massive Stars: The Inertial-inflow Model

Dust evolution across the Horsehead nebula

Efficient Methanol Production on the Dark Side of a Prestellar Core

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