Dust Migration and Morphology in Optically Thin Circumstellar Gas Disks

By T. Takeuchi, P. Artymowicz. 2000

155 citations recorded by the source corpus.

We analyze the dynamics of gas-dust coupling in the presence of stellar radiation pressure in circumstellar disks, which are in a transitional stage between the gas-dominated, optically thick, primordial nebulae, and the dust-dominated, optically thin Vega-type disks. Dust grains undergo radial migration, either leaving the disk owing to a strong radiation pressure or seeking a stable equilibrium orbit in corotation with gas. In our models of A-type stars surrounded by a total gas mass from a fraction to dozens of Earth masses, the outward migration speed of dust is comparable with the gas sound speed. Equilibrium orbits are circular, with exception of those significantly affected by radiation pressure, which can be strongly elliptic with apocenters extending beyond the bulk of the gas disk. The migration of dust gives rise to radial fractionation of dust and creates a variety of possible observed disk morphologies, which we compute by considering the equilibrium between the dust production and the dust-dust collisions removing particles from their equilibrium orbits. Large grains (typically ≳200 μm) are distributed throughout most of the gas disk. Smaller grains (in the range of 10-200 μm) concentrate in a prominent ring structure in the outer region of the gas disk (presumably at radius ~100 AU), where gas density is rapidly declining with radius. The width and density, as well as density contrast of the dust ring with respect to the inner dust disk, depend on the distribution of gas and the mechanical strength of the particles. Our results open the prospect for deducing the distribution of gas in circumstellar disks by observing their dust. We have qualitatively compared our models with two observed transitional disks around HR 4796A and HD 141569A. Dust migration can result in observation of a ring or a bimodal radial dust distribution, possibly very similar to the ones produced by gap-opening planets embedded in the disk, or shepherding it from inside or outside. We conclude that a convincing planet detection via dust imaging should include specific nonaxisymmetric structure (spiral waves, streamers, resonant arcs) following from the dynamical simulations of perturbed disks.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4920fb7bf0783b0ecb027c5b93fbc53a264bad1f

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Citations in the corpus

Dust distributions in debris disks: effects of gravity, radiation pressure and collisions (2006, background): “…dynamics of disks at transitional phases between protoplanetary and debris disks, exemplified by β Pic, AU Mic, HR4796A and similar objects, which may have retained gas in moderate amounts, still sufficient to influence the dust dynamics (e.g., Takeuchi & Artymowicz 2001; Thébault & Augereau 2005).”
Variations on Debris Disks: Icy Planet Formation at 30-150 AU for 1-3 M☉ Main-Sequence Stars (2008, methodology): “Current theoretical analyses support this idea (Burns et al. 1979; Artymowicz 1988; Takeuchi & Artymowicz 2001; Grigorieva et al. 2007).”
The Insignificance of P-R drag in detectable extrasolar planetesimal belts (2005, background): “…holes may be explained by the sublimation of icy grains (Jura et al. 1998) or by the outward migration of dust to the outer edge of a gas disk (Takeuchi & Artymowicz 2001), and clumps may arise from the destruction of planetesimals which were trapped in resonance with a planet when it…”
Gas Flow across Gaps in Protoplanetary Disks (2005, background): “However, alternative explanations for apparent holes have been offered for some cases, such as dust segregation (Takeuchi & Artymowicz 2001).”
Dust flow in gas disks in the presence of embedded planets (2006, background): “Haghighipour & Boss (2003) studied dust migration in a nonuniform axisymmetric nebula, and Takeuchi & Artymowicz (2001) investigated the effect of a sharp disk edge on dust migration.”
FORMATION AND EVOLUTION OF PLANETARY SYSTEMS: PROPERTIES OF DEBRIS DUST AROUND SOLAR-TYPE STARS (2008, background): “The dynamics of dust grains in optically thin systems are dominated by radiative and collisional processes when the effects of gas drag are negligible (Takeuchi & Artymowicz 2001).”
TOWARD A DETERMINISTIC MODEL OF PLANETARY FORMATION. VI. DYNAMICAL INTERACTION AND COAGULATION OF MULTIPLE ROCKY EMBRYOS AND SUPER-EARTH SYSTEMS AROUND SOLAR-TYPE STARS (2010, background): “Due to Pointing–Robertson drag, modest (submillimeter) grains undergo orbital decay on a timescale (a few Myr) shorter than the age of their host stars (e.g., Takeuchi & Artymowicz 2001).”
The Truncated Disk of CoKu Tau/4 (2004, background): “In debris disks around A stars young enough for some gas still to be present, it has been predicted that the combined effects of radiation pressure and gas drag would lead to central clearings in the distribution of small grains (Takeuchi and Artymowicz 2001).”
Spitzer IRS Spectroscopy of IRAS-discovered Debris Disks (2006, background): “Nu- merical models of disks with gas:dust ratios of 0.1 - 10 suggest that gas-grain interactions may generate the observed infrared bright rings by concentrating small grains, with radii just above the blowout radius, at the outer edge of the gas disk (Takeuchi & Artymowicz 2001).”
Young Stars Near the Sun (2004, background): “In addition, the dynamical behavior of dust particles can be complicated by gas-dust coupling resulting from gas present out to ∼100 AU (Zuckerman et al. 1995, Takeuchi & Artymowicz 2001).”
H2 and CO Emission from Disks around T Tauri and Herbig Ae Pre-Main-Sequence Stars and from Debris Disks around Young Stars: Warm and Cold Circumstellar Gas (2001, background): “Takeuchi & Artymowicz (2001) modeled the evolution of dust grains in disks with gas masses up to a few tens of Earth masses, comparable to that found for β Pictoris.”
Planets opening dust gaps in gas disks (2004, methodology): “We consider only spherical particles with radius s, and for the particle sizes we are interested in (s ≈ 1 mm) we can safely use Epsteins drag law (Takeuchi & Artymowicz 2001).”
The Size Distribution of Kuiper Belt Objects (2004, background): “Thus, disruptive collisions grind leftover planetesimals into small dust grains, which are removed by radiation pressure and Poynting-Robertson drag (see, e.g., Burns et al. 1979; Takeuchi & Artymowicz 2001).”
Dust filtration at gap edges: Implications for the spectral energy distributions of discs with embedded planets (2006, background): “Protoplanetary disc models that include some or all of these effects (Takeuchi & Artymowicz 2001; Kenyon & Bromley 2004; Dullemond & Dominik 2005; Takeuchi, Clarke & Lin 2005) admit the formation of dusty rings and inner holes, even in the absence of planets and gas.”
Dust Dynamics, Surface Brightness Profiles, and Thermal Spectra of Debris Disks: The Case of AU Microscopii (2005, background): “Ideas proposed by Takeuchi & Artymowicz (2001) and Klahr & Lin 10 That the color of β Pic’s outer disk is red rather than blue (by contrast to the case of AU Mic) could be a consequence of the particular grain size required for blow-out in the β Pic system, since for certain grain sizes and…”
Radial Flow of Dust Particles in Accretion Disks (2002, methodology): “Then, the non-dimensional stopping time Ts, as given by Takeuchi & Artymowicz (2001), is Ts = ρpsvK,mid ρgrvT , (20) where ρp is the particle internal density, s is the particle radius, and the mean thermal velocity is vT = √ 8/πc 2.”
Hubble Space Telescope ACS Coronagraphic Imaging of the Circumstellar Disk around HD 141569A (2003, background): “Moreover, Takeuchi & Artymowicz (2001) argue that the creation of a circular depleted region by an outwardly migrating planet is unlikely.”
Collisional Cascades in Planetesimal Disks. II. Embedded Planets (2003, methodology): “If the gas density in the disk is modest, coupling between the gas and the dust can produce rings and gaps (Takeuchi & Artymowicz 2001).”