Effect of dust grains size distribution on the Bohm sheath criterion in plasmas

Context. The size and chemical composition of interstellar dust grains are critical in setting the dynamical, physical, and chemical evolution of all the media in which they are present. Thanks to facilities such as the Atacama Large Millimeter/submillimeter Array (ALMA) and, in the future, the Square Kilometer Array (SKA), thermal emission in the (sub)millimetre to centimetre domain has become a very convenient way to trace grain properties. Aims. Our aim is to understand the influence of the composition and size distribution of dust grains on the shape of their spectral energy distribution (peak position, spectral index) in dense interstellar regions such as molecular clouds, prestellar cores, young stellar objects, and protoplanetary discs. Methods. Starting from the optical constants defined in The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS) for amorphous hydrogenated carbon grains and amorphous silicates in addition to water ice, we defined six material mixtures that we believe are representative of the expected dust composition in dense interstellar regions. The optical properties of 0.01 μm to 10 cm grains were then calculated with effective medium and Mie theories. The corresponding spectral energy distributions were subsequently calculated for isolated clouds either externally heated by the standard interstellar radiation field alone or in addition to an internal source. Results. The three main outcomes of this study are as follows. Firstly, the dust mass absorption coefficient strongly depends on both grain composition and size distribution potentially leading to errors in dust mass estimates by factors up to ~3 and 20, respectively. Secondly, it appears almost impossible to retrieve the grain composition from the (sub)millimetre to centimetre thermal emission shape alone as its spectral index for λ ≳ 3 mm does not depend on dust composition. Thirdly, using the “true” dust opacity spectral index to estimate grain sizes may lead to erroneous findings as the observed spectral index can be highly modified by the dust temperature distribution along the line of sight, which depends on the specific heating source and on the geometry of the studied interstellar region. Conclusions. Based on the interpretation of only the spectral shape of (sub)millimetre to centimetre observational data, the determination of the dust masses, compositions, and sizes are highly uncertain.

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Pseudopotential approach for dust acoustic solitary waves in dusty plasmas with kappa-distributed ions and electrons and dust grains having power law size distribution

Physics of Plasmas ◽

10.1063/1.4919259 ◽

2015 ◽

Vol 22 (4) ◽

pp. 043708 ◽

Cited By ~ 8

Author(s):

Gadadhar Banerjee ◽

Sarit Maitra

Keyword(s):

Size Distribution ◽

Solitary Waves ◽

Power Law ◽

Dusty Plasmas ◽

Dust Grains ◽

Dust Acoustic Solitary Waves ◽

Dust Acoustic ◽

Pseudopotential Approach

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Rapid elimination of small dust grains in molecular clouds

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038063 ◽

2020 ◽

Vol 641 ◽

pp. A39 ◽

Cited By ~ 1

Author(s):

Kedron Silsbee ◽

Alexei V. Ivlev ◽

Olli Sipilä ◽

Paola Caselli ◽

Bo Zhao

Keyword(s):

Size Distribution ◽

Cosmic Ray ◽

Ionization Rate ◽

Microwave Emission ◽

Dust Grains ◽

Gas Temperature ◽

Neutral Gas ◽

Cloud Cores ◽

The Impact ◽

Small Dust

We argue that impact velocities between dust grains with sizes of less than ∼0.1 μm in molecular cloud cores are dominated by drift arising from ambipolar diffusion. This effect is due to the size dependence of the dust coupling to the magnetic field and the neutral gas. Assuming perfect sticking in collisions up to ≈50 m s−1, we show that this effect causes rapid depletion of small grains, consistent with starlight extinction and IR and microwave emission measurements, both in the core center (n ∼ 106 cm−3) and envelope (n ∼ 104 cm−3). The upper end of the size distribution does not change significantly if only velocities arising from this effect are considered. We consider the impact of an evolved grain-size distribution on the gas temperature, and argue that if the depletion of small dust grains occurs as expected from our model, then the cosmic ray ionization rate must be well below 10−16 s−1 at a number density of 105 cm−3.

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Effects of dust size distribution on nonlinear magnetosonic wave in a dusty plasma

Modern Physics Letters B ◽

10.1142/s0217984921501219 ◽

2020 ◽

pp. 2150121

Author(s):

Bo Liu ◽

Juan Fang Han ◽

Wen Shan Duan

Keyword(s):

Solitary Wave ◽

Size Distribution ◽

Dusty Plasma ◽

Propagation Velocity ◽

Magnetosonic Wave ◽

Dust Grains ◽

Minimum Radius ◽

Dust Size Distribution ◽

The Difference ◽

Dust Grain

Both the linear and the nonlinear magnetosonic wave in a multi-component dusty plasma are studied in the present paper. The dependence of the dispersion relation of the linear waves on the dust size distribution are given. It seems that the larger the difference between the maximum and the minimum radius of the dust grains, the lower the wave frequency for all cases of the dust size distribution. Furthermore, it is noted that the width, the amplitude and the propagation velocity of the KdV solitary wave depend on the dust size distribution, especially it depend on whether the number density of the larger sized dust grain is larger or smaller than that of the smaller sized dust grain. For the power law dust size distribution, the width and the propagation velocity of the KdV solitary wave between the maximum and the minimum radius of the dust grains is larger than that of mono-sized dusty plasma.

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The size distribution of dust grains in single clouds - II. The analysis of extinction using inhomogeneous grains

Monthly Notices of the Royal Astronomical Society ◽

10.1046/j.1365-8711.1998.01048.x ◽

1998 ◽

Vol 294 (4) ◽

pp. 548-556 ◽

Cited By ~ 8

Author(s):

Zubko ◽

Krelowski ◽

Wegner

Keyword(s):

Size Distribution ◽

Dust Grains

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Effects of rotational disruption on the evolution of grain size distribution in galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa793 ◽

2020 ◽

Vol 494 (1) ◽

pp. 1058-1070 ◽

Cited By ~ 2

Author(s):

Hiroyuki Hirashita ◽

Thiem Hoang

Keyword(s):

Grain Size ◽

Tensile Strength ◽

Size Distribution ◽

Galaxy Evolution ◽

Grain Size Distribution ◽

Extinction Curve ◽

Short Time Scale ◽

Dust Grains ◽

Grain Production ◽

Dust Temperature

ABSTRACT Interstellar dust grains can be spun up by radiative torques, and the resulting centrifugal force may be strong enough to disrupt large dust grains. We examine the effect of this rotational disruption on the evolution of grain size distribution in galaxies. To this goal, we modify our previous model by assuming that rotational disruption is the major small-grain production mechanism. We find that rotational disruption can have a large influence on the evolution of grain size distribution in the following two aspects especially for composites and grain mantles (with tensile strength ∼107 erg cm −3). First, because of the short time-scale of rotational disruption, the small-grain production occurs even in the early phase of galaxy evolution. Therefore, even though stars produce large grains, the abundance of small grains can be large enough to steepen the extinction curve. Secondly, rotational disruption is important in determining the maximum grain radius, which regulates the steepness of the extinction curve. For compact grains with tensile strength ≳109 erg cm −3, the size evolution is significantly affected by rotational disruption only if the radiation field is as strong as (or the dust temperature is as high as) expected for starburst galaxies. For compact grains, rotational disruption predicts that the maximum grain radius becomes less than 0.2 $\rm{\mu m}$ for galaxies with a dust temperature ≳50 K.

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Evolution of grain size distribution in galactic discs

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937087 ◽

2020 ◽

Vol 636 ◽

pp. A18 ◽

Cited By ~ 2

Author(s):

M. Relaño ◽

U. Lisenfeld ◽

K.-C. Hou ◽

I. De Looze ◽

J. M. Vílchez ◽

...

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Radial Distribution ◽

Molecular Gas ◽

Evolutionary Stage ◽

Dust Grains ◽

Cosmological Simulations ◽

Dust Grain ◽

Dust Evolution

Context. Dust is formed out of stellar material and it is constantly affected by different mechanisms occurring in the interstellar medium. Depending on their size, the behaviour of dust grains vary under these mechanisms and, therefore, the dust grain size distribution evolves as part of the dust evolution itself. Following how the grain size distribution evolves is a difficult computing task that has only recently become the subject of consideration. Smoothed particle hydrodynamic (SPH) simulations of a single galaxy, together with cosmological simulations, are producing the first predictions of the evolution of dust grain size distribution. Aims. We compare, for the first time, the evolution of the dust grain size distribution as predicted by SPH simulations and results from observations. We are able to validate not only the predictions of the evolution of the small-to-large grain mass ratio (DS/DL) within a galaxy, but we also provide observational constraints for recent cosmological simulations that include the grain size distribution in the dust evolution framework. Methods. We selected a sample of three spiral galaxies with different masses: M 101, NGC 628, and M 33. We fitted the dust spectral energy distribution across the disc of each object and derived the abundance of the different grain types included in the dust model. We analysed how the radial distribution of the relative abundance of the different grain size populations changes over the whole disc within each galaxy. The DS/DL ratio as a function of the galactocentric distance and metallicity is directly compared to what has been predicted by the SPH simulations. Results. We find a good agreement between the observed radial distribution of DS/DL and what was obtained from the SPH simulations of a single galaxy. The comparison agrees with the expected evolutionary stage of each galaxy. We show that the central parts of NGC 628 at a high metallicity and with a high molecular gas fraction are mainly affected not only by accretion, but also by the coagulation of dust grains. The centre of M 33, having a lower metallicity and lower molecular gas fraction, presents an increase in the DS/DL ratio, demonstrating that shattering is very effective for creating a large fraction of small grains. Finally, the observational results provided by our galaxies confirm the general relations predicted by the cosmological simulations based on the two-grain size approximation. However, we also present evidence that the simulations could be overestimating the amount of large grains in high massive galaxies.

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Size Distribution of Dust grains in Vortices in a Protoplanetary Disk

10.1063/1.3215818 ◽

2009 ◽

Author(s):

Eri Kawamura ◽

Sei-ichiro Watanabe ◽

Tomonori Usuda ◽

Motohide Tamura ◽

Miki Ishii

Keyword(s):

Size Distribution ◽

Protoplanetary Disk ◽

Dust Grains

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