Momentum transfer to fluffy dust aggregates from stellar winds

Minato, T.; Koehler, Melanie; Kimura, Hiroshi; Mann, Ingrid; Yamamoto, Tetsuo

doi:10.1051/0004-6361:20054774

Cited by 52 publications

(66 citation statements)

References 28 publications

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“…For carbonaceous particles orbiting the Sun, Minato et al (2004Minato et al ( , 2006 find γ ∼ 1. Kobayashi et al (2011) argue that the pile-up scenario could work for Vega if the disk is drag-dominated, which requires γ ≈ 300.…”

Section: Stellar Wind Dragmentioning

confidence: 99%

Near-infrared emission from sublimating dust in collisionally active debris disks

Lieshout

Dominik

Kama

et al. 2014

A&A

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Context. Hot exozodiacal dust is thought to be responsible for excess near-infrared (NIR) emission emanating from the innermost parts of some debris disks. The origin of this dust, however, is still a matter of debate. Aims. We test whether hot exozodiacal dust can be supplied from an exterior parent belt by Poynting-Robertson (P-R) drag, paying special attention to the pile-up of dust that occurs owing to the interplay of P-R drag and dust sublimation. Specifically, we investigate whether pile-ups still occur when collisions are taken into account, and if they can explain the observed NIR excess. Methods. We computed the steady-state distribution of dust in the inner disk by solving the continuity equation. First, we derived an analytical solution under a number of simplifying assumptions. Second, we developed a numerical debris disk model that for the first time treats the complex interaction of collisions, P-R drag, and sublimation in a self-consistent way. From the resulting dust distributions, we generated thermal emission spectra and compare these to observed excess NIR fluxes. Results. We confirm that P-R drag always supplies a small amount of dust to the sublimation zone, but find that a fully consistent treatment yields a maximum amount of dust that is about 7 times lower than that given by analytical estimates. The NIR excess due to this material is much less ( < ∼ 10 −3 for A-type stars with parent belts at > ∼ 1 AU) than the values derived from interferometric observations (∼10 −2 ). Pile-up of dust still occurs when collisions are considered, but its effect on the NIR flux is insignificant. Finally, the cross-section in the innermost regions is clearly dominated by barely bound grains.

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Section: Stellar Wind Dragmentioning

confidence: 99%

Near-infrared emission from sublimating dust in collisionally active debris disks

Lieshout

Dominik

Kama

et al. 2014

A&A

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“…An accurate prescription for the latter property is very important, as it plays a critical role in the determination of the relative velocities among the dust aggregates. In Paper I we explicitly follow both σ and m, i.e., σ is not a priori assumed to be a function of m as, e.g., for compact spheres (σ ∝ m 2/3 ) or very fluffy particles σ ∝ m (Minato et al 2006).…”

Section: Application To Molecular Cloud Coresmentioning

confidence: 99%

Dust coagulation and fragmentation in molecular clouds

Ormel

Min

Tielens

et al. 2011

A&A

157

180

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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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“…Using momentum-transfer cross-sections of particles of mass m from the stellar radiation, C pr , and from the stellar wind, C sw , the ratios β and β sw are given by (Gustafson 1994;Minato et al 2004;2006),…”

Section: Equation Of Motionmentioning

confidence: 99%

“…implying that the stellar wind drag is important unless L /Ṁ L /Ṁ , whereṀ is the mass loss rate of the present Sun by the solar wind (Minato et al 2006). On the other hand, the ratio of the wind to radiation pressure forces is evaluated to be…”

Section: Equation Of Motionmentioning

confidence: 99%

Dust ring formation due to sublimation of dust grains drifting radially inward by the Poynting–Robertson drag: An analytical model

Kobayashi

Watanabe

Kimura

et al. 2009

Icarus

107

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Dust particles exposed to the stellar radiation and wind drift radially inward by the Poynting-Robertson (P-R) drag and pile up at the zone where they begin to sublime substantially. The reason they pile up or form a ring is that their inward drifts due to the P-R drag are suppressed by stellar radiation pressure when the ratio of radiation pressure to stellar gravity on them increases during their sublimation phases. We present analytic solutions to the orbital and mass evolution of such subliming dust particles, and find their drift velocities at the pileup zone are almost independent of their initial semimajor axes and masses. We derive analytically an enhancement factor of the number density of the particles from their drift velocities at the outer edge of the sublimation zone.We show that the formula of the enhancement factor reproduces well numerical simulations in the previous studies. The enhancement factor for spherical dust particles of silicate and carbon extends from 3 to more than 20 at stellar luminosities L = 0.8-500L , where L is solar luminosity. Although the enhancement factor for fluffy dust particles is smaller than that for spherical particles, sublimating particles inevitably form a dust ring as long as their masses decrease faster than their surface areas during sublimation. The formulation is applicable to dust ring formation for arbitrary shape and material of dust in dust-debris disks as well as in the Solar System.-4 -

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Momentum transfer to fluffy dust aggregates from stellar winds

Cited by 52 publications

References 28 publications

Near-infrared emission from sublimating dust in collisionally active debris disks

Near-infrared emission from sublimating dust in collisionally active debris disks

Dust coagulation and fragmentation in molecular clouds

Dust ring formation due to sublimation of dust grains drifting radially inward by the Poynting–Robertson drag: An analytical model

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