Grain Retention and Formation of Planetesimals near the Snow Line in MRI-driven Turbulent Protoplanetary Disks

By K. Kretke, D. Lin. 2007

193 citations recorded by the source corpus.

The first challenge in the formation of both terrestrial planets and the cores of gas giants is the retention of grains in protoplanetary disks. In most regions of these disks, gas attains sub-Keplerian speeds as a consequence of a negative pressure gradient. Hydrodynamic drag leads to orbital decay and depletion of the solid material in the disk, with characteristic timescales as short as only a few hundred years for meter-sized objects at 1 AU. In this Letter, we suggest a particle retention mechanism that promotes the accumulation of grains and the formation of planetesimals near the water sublimation front or "snow line." This model is based on the assumption that, in the regions most interesting for planet formation, the viscous evolution of the disk is due to turbulence driven by the magnetorotational instability (MRI) in the surface layers of the disk. The depth to which MRI effectively generates turbulence is a strong function of grain size and abundance. A sharp increase in the grain-to-gas density ratio across the snow line reduces the column depth of the active layer. As the disk evolves toward a quasi-steady state, this change in the active layer creates a local maximum in radial distribution of the gas surface density and pressure, causing the gas to rotate at super-Keplerian speed and halting the inward migration of grains. This scenario presents a robust process for grain retention that may aid in the formation of proto-gas giant cores preferentially near the snow line.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/5aacfb1a31e6f604afed18a4209fbda0781db549

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

FORMATION OF THE TERRESTRIAL PLANETS FROM A NARROW ANNULUS (2009, background): “…active and dead zones in a protoplanetary disk may mark a transition from laminar behavior to turbulent behavior, which may also affect the manner in which migration occurs (Rice & Armitage 2003; Johnson et al. 2006), and density gradients at the interface may also contribute (Kretke & Lin 2007).”
Forming the cores of giant planets from the radial pebble flux in protoplanetary discs (2014, background): “In these regions we can expect particle growth to large pebble sizes and large pebble surface densities (Ros & Johansen 2013), possibly aided by the emergence of a pressure bump (Kretke & Lin 2007).”
Dead Zone Accretion Flows in Protostellar Disks (2008, background): “Possibly the inflowing gas will pile up at some location, leading to the development of a local radial pressure maximum (Kretke & Lin 2007).”
Possible planet-forming regions on submillimetre images (2011, background): “Kretke & Lin (2007) have already shown that pressuregradient inversion formed at the inner edge of the dead zone or at the snow line causes the accumulation of dust.”
Dust size distributions in coagulation/fragmentation equilibrium: numerical solutions and analytical fits (2010, background): “Possible solutions to reduce the drift rate include bumps in the radial pressure profile (see Kretke & Lin 2007; Brauer et al. 2008b; Cossins et al. 2009) or zonal flows (see Johansen et al. 2009).”
Dust Evolution and the Formation of Planetesimals (2016, background): “The cause of such a pressure bump could be either a planet embedded in the disk, or variations in the viscosity profile (e.g., Kretke & Lin 2007; Regály et al. 2012).”
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): “For a range of disk accretion rate (comparable to that observed in typical T Tauri stars), migration of embryos formed in the outer regions of protostellar disks is stalled by a barrier near the ice line (Kretke & Lin 2007; Paper V).”
Planetesimal formation near the snowline: in or out? (2017, background): “So-called “dead zones”, where turbulence is strongly reduced, could occur at locations in the disk with a sharp increase in the solids-to-gas ratio (Kretke & Lin 2007).”
The great dichotomy of the Solar System: Small terrestrial embryos and massive giant planet cores (2015, background): “It has been proposed (Kretke and Lin, 2007) that the snowline can create a pressure bump because the condensation of icy grain could strongly reduce the viscosity of the gas, thus increasing the gas surface density at the snowline location.”
EVIDENCE OF FAST PEBBLE GROWTH NEAR CONDENSATION FRONTS IN THE HL TAU PROTOPLANETARY DISK (2015, background): “…Pasadena, CA 91125, USA 3 Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, Michigan 48109, USA bilities that form planetesimals (Kretke & Lin 2007; Brauer et al. 2008; Ros & Johansen 2013; Bitsch et al. 2014; Dra̧żkowska & Dullemond 2014; Flock et al. 2015).”
Planetesimal formation starts at the snow line (2017, background): “Such a rapid change of conditions may contribute to a pressure bump build-up that would halt the radial drift of solids thus facilitating planet formation (Kretke & Lin 2007; Brauer et al. 2008; Dra̧żkowska et al. 2013).”
Astrophysics with Extraterrestrial Materials (2016, background): “Solids may also become concentrated in localized pressure gradients that arise from nonuniform evolution of the protoplanetary disk (e.g., Kretke & Lin 2007, Tan et al. 2015).”
Prograde rotation of protoplanets by accretion of pebbles in a gaseous environment (2009, background): “Recent studies have shown how planetesimal formation by self-gravity (Johansen et al. 2007; Kato et al. 2009) and by coagulation (Kretke & Lin 2007; Brauer, Henning, & Dullemond 2008) proceed in such convergence regions in the flow of solid particles.”
Gas- and dust evolution in protoplanetary disks (2010, background): “Taken together, these facts make environments as the inner edge of dead zones ideal places for grain growth (see Brauer et al. 2008b; Kretke & Lin 2007): shutting of MRI leads to low values ofα, which are needed to reduce turbulent relative velocities and the low pressure gradients prevent radial…”
THE MASS AND SIZE DISTRIBUTION OF PLANETESIMALS FORMED BY THE STREAMING INSTABILITY. I. THE ROLE OF SELF-GRAVITY (2015, background): “For example, pressure bumps due to zonal flows (Johansen et al. 2009a; Simon & Armitage 2014), ice lines (Kretke & Lin 2007; but see Yang & Menou 2010 and Bitsch et al. 2014), and abrupt transitions in ionization fraction (Dzyurkevich et al. 2010; Dra̧żkowska et al. 2013) may stop or slow this…”
How to form planetesimals from mm-sized chondrules and chondrule aggregates (2015, background): “This can occur as part of a large-scale pressure bump, which could form around the snow line (Kretke & Lin 2007).”