Scattering of small bodies by planets: a potential origin for exozodiacal dust?

Bonsor, Amy; Augereau, J.-C.; Thébault, P.

doi:10.1051/0004-6361/201220005

Cited by 76 publications

(75 citation statements)

References 61 publications

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“…When JFC orbits cross the current snow line, they begin to sublimate and eventually disintegrate, releasing dust. Simulations of generic planetary systems also show that a chain of several planets is required to efficiently transport planetesimals inward from an outer reservoir (Bonsor et al 2012(Bonsor et al , 2014. This is consistent with the idea that the region between the snow line and the cold belt is maintained by one or more planets .…”

Section: Hypothesis 2: Inward Transport and The Current Snow Linesupporting

confidence: 72%

What Sets the Radial Locations of Warm Debris Disks?

Ballering

Rieke

et al. 2017

ApJ

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The architectures of debris disks encode the history of planet formation in these systems. Studies of debris disks via their spectral energy distributions (SEDs) have found infrared excesses arising from cold dust, warm dust, or a combination of the two. The cold outer belts of many systems have been imaged, facilitating their study in great detail. Far less is known about the warm components, including the origin of the dust. The regularity of the disk temperatures indicates an underlying structure that may be linked to the water snow line. If the dust is generated from collisions in an exo-asteroid belt, the dust will likely trace the location of the water snow line in the primordial protoplanetary disk where planetesimal growth was enhanced. If instead the warm dust arises from the inward transport from a reservoir of icy material farther out in the system, the dust location is expected to be set by the current snow line. We analyze the SEDs of a large sample of debris disks with warm components. We find that warm components in single-component systems (those without detectable cold components) follow the primordial snow line rather than the current snow line, so they likely arise from exo-asteroid belts. While the locations of many warm components in two-component systems are also consistent with the primordial snow line, there is more diversity among these systems, suggesting additional effects play a role.

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Section: Hypothesis 2: Inward Transport and The Current Snow Linesupporting

confidence: 72%

What Sets the Radial Locations of Warm Debris Disks?

Ballering

Rieke

et al. 2017

ApJ

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“…Bonsor et al (2012) investigated this scenario and find that it is marginally capable of providing mass influxes compatible with observations. However, this requires relatively contrived planetary system architectures, consisting of closely packed chains of low-mass planets.…”

Section: Other Explanations For Hot Exozodiacal Dustmentioning

confidence: 83%

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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“…A rather contrived set of planetary system properties would be needed to result in detectable hot dust from an outer planetesimal belt that lies below the detection threshold (Bonsor et al 2012), and so this is unlikely to be the origin of hot dust-only systems like HD172555. However, this is a reasonable proposition for young systems with hot and cold dust, particularly if the early phase in the system's evolution is characterised by dynamical settling and so intense cometary activity (Bonsor et al 2013a).…”

Section: Evolution Of Hot Dust In Inner Regionsmentioning

confidence: 99%

Five steps in the evolution from protoplanetary to debris disk

Wyatt

Panić

Kennedy

et al. 2015

Astrophys Space Sci

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The protoplanetary disks seen around Herbig Ae stars eventually dissipate leaving just a tenuous debris disk, comprised of planetesimals and the dust derived from them, as well as possibly gas and planets. This paper uses the properties of the youngest (10-20 Myr) A star debris disks to consider the transition from protoplanetary to debris disk. It is argued that the physical distinction between these two classes should rest on the presence of primordial gas in sufficient quantities to dominate the motion of small dust grains (rather than on the secondary nature of the dust or its level of stirring). This motivates an observational classification based on the dust emission spectrum which is empirically defined so that A star debris disks require fractional excesses < 3 at 12 µm and < 2000 at 70 µm. We also propose that a useful hypothesis to test is that the planet and planetesimal systems seen on the main sequence are already in place during the protoplanetary disk phase, but are obscured or overwhelmed by the rest of the disk. This may be only weakly true if the architecture of the planetary system continues to change until frozen at the epoch of disk dispersal, or completely false if planets and planetesimals form during the relatively short dispersal phase. Five steps in the transition are discussed: (i) the well-known carving of an inner hole to form a transition disk ; (ii) depletion of mm-sized dust in the outer disk, where it is noted that it is of critical importance to ascertain whether this mass ends up in larger planetesimals or is collisionally depleted; (iii) final clearing of inner regions, where it is noted that multiple debris-like mechanisms exist to replenish moderate levels of hot dust atInstitute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK later phases, and that these likely also operate in protoplanetary disks; (iv) disappearence of the gas, noting the recent discoveries of both primordial and secondary gas in debris disks which highlight our ignorance in this area and its impending enlightenment by ALMA; (v) formation of ring-like structure of planetesimals, noting that these are shaped by interactions with planets, and that the location of the planetesimals in protoplanetary disks may be unrelated to that of dust concentrations therein that are set by gas interactions.

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Scattering of small bodies by planets: a potential origin for exozodiacal dust?

Cited by 76 publications

References 61 publications

What Sets the Radial Locations of Warm Debris Disks?

What Sets the Radial Locations of Warm Debris Disks?

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

Five steps in the evolution from protoplanetary to debris disk

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