Dust coagulation and fragmentation in molecular clouds

Ormel, Chris W.; Paszun, D.; Dominik, C.; Tielens, A. G. G. M.

doi:10.1051/0004-6361/200811158

Cited by 246 publications

(361 citation statements)

References 66 publications

(87 reference statements)

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“…The scattering feature before the edge is better fitted using a model with larger particles, which leads to the possibility of the presence of particles larger than 0.25 µm. It is possible that in environments such as the Galactic center region we observe a substantial amount of particles larger than 0.25 µm (Ossenkopf et al 1992;Ormel et al 2009Ormel et al , 2011. In our analysis, we assume that the dust particles are solid spheres, while it is more likely that large particles in dense environments are grown by coagulation of dust particles (Jura 1980).…”

Section: Scattering and Particle Size Distributionsmentioning

confidence: 98%

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Absorption and scattering by interstellar dust in the silicon K-edge of GX 5-1

Zeegers

Costantini

Vries

et al. 2017

A&A

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Context. We study the absorption and scattering of X-ray radiation by interstellar dust particles, which allows us to access the physical and chemical properties of dust. The interstellar dust composition is not well understood, especially on the densest sight lines of the Galactic Plane. X-rays provide a powerful tool in this study. Aims. We present newly acquired laboratory measurements of silicate compounds taken at the Soleil synchrotron facility in Paris using the Lucia beamline. The dust absorption profiles resulting from this campaign were used in this pilot study to model the absorption by interstellar dust along the line of sight of the low-mass X-ray binary (LMXB) GX 5-1. Methods. The measured laboratory cross-sections were adapted for astrophysical data analysis and the resulting extinction profiles of the Si K-edge were implemented in the SPEX spectral fitting program. We derive the properties of the interstellar dust along the line of sight by fitting the Si K-edge seen in absorption in the spectrum of GX 5-1. Results. We measured the hydrogen column density towards GX 5-1 to be 3.40 ± 0.1 × 10 22 cm −2 . The best fit of the silicon edge in the spectrum of GX 5-1 is obtained by a mixture of olivine and pyroxene. In this study, our modeling is limited to Si absorption by silicates with different Mg:Fe ratios. We obtained an abundance of silicon in dust of 4.0 ± 0.3 × 10 −5 per H atom and a lower limit for total abundance, considering both gas and dust, of > 4.4 × 10 −5 per H atom, which leads to a gas to dust ratio of > 0.22. Furthermore, an enhanced scattering feature in the Si K-edge may suggest the presence of large particles along the line of sight.

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Section: Scattering and Particle Size Distributionsmentioning

confidence: 98%

“…The sight line toward GX 5-1 traverses the molecular ring and likely probes a mixture of diffuse and dense medium. The dense region may be associated with the molecular ring, characterized by larger grains (Ormel et al 2009(Ormel et al , 2011.…”

Section: Scattering and Particle Size Distributionsmentioning

confidence: 99%

Absorption and scattering by interstellar dust in the silicon K-edge of GX 5-1

Zeegers

Costantini

Vries

et al. 2017

A&A

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“…Because the coagulation process itself as also the extinction properties depend strongly on the grain structure, much theoretical and experimental effort has focused on understanding the evolution of the porosity of collisional aggregates (Ossenkopf 1993;Dominik & Tielens 1997;Blum & Wurm 2008;Suyama et al 2008;Wada et al 2008;Okuzumi 2009). These studies show that initially coagulation may lead to the formation of open, fractal structures, but eventually, if collision velocities become high, compaction and then fragmentation will take over (Ormel et al 2009). As a result, the structure of the aggregates -and therefore the extinction properties -depend on the density and history of the cloud.…”

Section: Introductionmentioning

confidence: 99%

“…As a result, the structure of the aggregates -and therefore the extinction properties -depend on the density and history of the cloud. Recently, we have calculated the collisional growth of interstellar grains in dense clouds (Ormel et al 2009). Here, we examine the implications of this growth for the extinction behavior of dust in dense clouds.…”

Section: Introductionmentioning

confidence: 99%

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Dust coagulation and fragmentation in molecular clouds

Ormel

Min

Tielens

et al. 2011

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The dust size distribution in molecular clouds can be strongly affected by ice-mantle formation and (subsequent) grain coagulation. Following previous work where the dust size distribution has been calculated from a state-of-the art collision model for dust aggregates that involves both coagulation and fragmentation (Paper I), the corresponding opacities are presented in this study. The opacities are calculated by applying the effective medium theory assuming that the dust aggregates are a mix of 0.1 μm silicate and graphite grains and vacuum. In particular, we explore how the coagulation affects the near-IR opacities and the opacity in the 9.7 μm silicate feature. We find that as dust aggregates grow to μm-sizes both the near-IR color excess and the opacity in the 9.7 μm feature increases. Despite their coagulation, porous aggregates help to prolong the presence of the 9.7 μm feature. We find that the ratio between the opacity in the silicate feature and the near-IR color excess becomes lower with respect to the ISM, in accordance with many observations of dark clouds. However, this trend is primarily a result of ice mantle formation and the mixed material composition of the aggregates, rather than being driven by coagulation. With stronger growth, when most of the dust mass resides in particles of size ∼10 μm or larger, both the near-IR color excess and the 9.7 μm silicate feature significantly diminish. Observations at additional wavelengths, in particular in the sub-mm range, are essential to provide quantitative constraints on the dust size distribution within dense cores. Our results indicate that the sub-mm index β will increase appreciably, if aggregates grow to ∼100 μm in size.

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Dust Evolution in Protoplanetary Disks

Andrews¹,

Birnstiel²

2018

Handbook of Exoplanets

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Over the past decade, advancement of observational capabilities, specifically the Atacama Large Millimeter/submillimeter Array (ALMA) and SPHERE instrument, alongside theoretical innovations like pebble accretion, have reshaped our understanding of planet formation and the physics of protoplanetary disks. Despite this progress, mysteries persist along the winded path of micrometer-sized dust, from the interstellar medium, through transport and growth in the protoplanetary disk, to becoming gravitationally bound bodies. This review outlines our current knowledge of dust evolution in circumstellar disks, yielding the following insights:• Theoretical and laboratory studies have accurately predicted the growth of dust particles to sizes that are susceptible to accumulation through transport processes like radial drift and settling. • Critical uncertainties in that process remain the level of turbulence, the threshold collision velocities at which dust growth stalls, and the evolution of dust porosity. • Symmetric and asymmetric substructure are widespread. Dust traps appear to be solving several long-standing issues in planet formation models, and they are observationally consistent with being sites of active planetesimal formation. • In some instances, planets have been identified as the causes behind substructures. This underlines the need to study earlier stages of disks to understand how planets can form so rapidly.In the future, better probes of the physical conditions in optically thick regions, including densities, turbulence strength, kinematics, and particle properties will be essential for unraveling the physical processes at play.

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Dust coagulation and fragmentation in molecular clouds

Cited by 246 publications

References 66 publications

Absorption and scattering by interstellar dust in the silicon K-edge of GX 5-1

Absorption and scattering by interstellar dust in the silicon K-edge of GX 5-1

Dust coagulation and fragmentation in molecular clouds

Dust Evolution in Protoplanetary Disks

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