Shape effects and size distributions of astrophysical dust particles

Rakesh, K.; Botet, Robert

doi:10.1093/mnras/stx128

Cited by 4 publications

(3 citation statements)

References 40 publications

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“…In the context of BAM, further interesting studies are related to aggregation and fragmentation [16,18,22]. Incorporation of fragmentation indeed can provide information on more realistic scenario.…”

Section: Discussionmentioning

confidence: 99%

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Dimension dependence of clustering dynamics in models of ballistic aggregation and freely cooling granular gas

Paul

Das

2018

Phys. Rev. E

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Via event-driven molecular dynamics simulations we study kinetics of clustering in assemblies of inelastic particles in various space dimensions. We consider two models, viz., the ballistic aggregation model (BAM) and the freely cooling granular gas model (GGM), for each of which we quantify the time dependence of kinetic energy and average mass of clusters (that form due to inelastic collisions). These quantities, for both the models, exhibit power-law behavior, at least in the long time limit. For the BAM, corresponding exponents exhibit strong dimension dependence and follow a hyperscaling relation. In addition, in the high packing fraction limit the behavior of these quantities become consistent with a scaling theory that predicts an inverse relation between energy and mass. On the other hand, in the case of the GGM we do not find any evidence for such a picture. In this case, even though the energy decay, irrespective of packing fraction, matches quantitatively with that for the high packing fraction picture of the BAM, it is inversely proportional to the growth of mass only in one dimension, and the growth appears to be rather insensitive to the choice of the dimension, unlike the BAM.

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Section: Discussionmentioning

confidence: 99%

“…Growth in many physical situations occurs due to inelastic collisions among aggregates [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Typical examples [1, 4, 7, 9-12, 14, 16-18, 20-22] are growth of liquid droplets and solid clusters in upper atmosphere, clustering in cosmic dust, etc.…”

Section: Introductionmentioning

confidence: 99%

Dimension dependence of clustering dynamics in models of ballistic aggregation and freely cooling granular gas

Paul

Das

2018

Phys. Rev. E

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“…We reckon that modeling the amorphous carbon dust with fluffy grains might be more realistic compared to the usually adopted solid spheres. Amorphous carbon dust are structured in chain-like distributions (Rotundi et al 1998), whilst the optical and IR properties of graphite are less sensitive to shape (see Rai & Botet 2017). However, the exact empty fraction is unknown and limits the capability of the models to determine a more accurate 𝑀 dust .…”

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confidence: 99%

Carbon dust in the evolved born-again planetary nebulae A30 and A78

Toalá,

Jiménez-Hernández,

Rodríguez-González

et al. 2021

Preprint

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We present an infrared (IR) characterization of the born-again planetary nebulae (PNe) A 30 and A 78 using IR images and spectra. We demonstrate that the carbon-rich dust in A 30 and A 78 is spatially coincident with the H-poor ejecta and coexists with hot X-ray-emitting gas up to distances of 50 from the central stars (CSPNs). Dust forms immediately after the born-again event and survives for 1000 yr in the harsh environment around the CSPN as it is destroyed and pushed away by radiation pressure and dragged by hydrodynamical effects. Spitzer IRS spectral maps showed that the broad spectral features at 6.4 and 8.0 𝜇m, attributed to amorphous carbon formed in H-deficient environments, are associated with the disrupted disk around their CSPN, providing an optimal environment for charge exchange reactions with the stellar wind that produces the soft X-ray emission of these sources. Nebular and dust properties are modeled for A 30 with taking into account different carbonaceous dust species. Our models predict dust temperatures in the 40-230 K range, five times lower than predicted by previous works. Gas and dust masses for the born-again ejecta in A 30 are estimated to be 𝑀 gas = (4.41 +0.55 −0.14 ) ×10 −3 M and 𝑀 dust = (3.20 +3.21 −2.06 ) ×10 −3 M , which can be used to estimate a total ejected mass and mass-loss rate for the born-again event of (7.61 +3.76 −2.20 ) × 10 −3 M and 𝑀 = [5 − 60] × 10 −5 M yr −1 , respectively. Taking into account the carbon trapped into dust grains, we estimate that the C/O mass ratio of the H-poor ejecta of A 30 is larger than 1, which favors the very late thermal pulse model over the alternate hypothesis of a nova-like event.

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