scholarly journals Ice Condensation as a Planet Formation Mechanism

2013 ◽  
Vol 8 (S299) ◽  
pp. 382-383
Author(s):  
Katrin Ros
Keyword(s):  
Formation Mechanism ◽  
Time Scale ◽  
Planet Formation ◽  
Particle Growth ◽  
Dynamical Behaviour ◽  
Water Ice ◽  
Ice Particles ◽  
Size Evolution ◽  
Protoplanetary Discs

AbstractParticles in protoplanetary discs grow rapidly to millimetre-sizes via coagulation, but further growth to centimetre-sized pebbles is not yet completely understood. We investigate particle growth by ice condensation in a model where we take the dynamical behaviour of vapour and ice particles into account, as well as the size evolution due to condensation and sublimation. Our results show that efficient growth from dust to pebbles is possible close to the water ice line at ~3 AU, with particles growing from millimetres to decimetres on a time scale of 10000 yr.

scholarly journals Effect of nucleation on icy pebble growth in protoplanetary discs

2019 ◽  
Vol 629 ◽  
pp. A65 ◽  
Author(s):  
Katrin Ros ◽  
Anders Johansen ◽  
Ilona Riipinen ◽  
Daniel Schlesinger
Keyword(s):  
Water Vapour ◽  
Vapour Pressure ◽  
Particle Growth ◽  
Total Surface Area ◽  
Ice Nucleation ◽  
Solid Particles ◽  
Water Vapour Pressure ◽  
Water Ice ◽  
Protoplanetary Discs ◽  
Heterogeneous Ice Nucleation

Solid particles in protoplanetary discs can grow by direct vapour deposition outside of ice lines. The presence of microscopic silicate particles may nevertheless hinder growth into large pebbles, since the available vapour is deposited predominantly on the small grains that dominate the total surface area. Experiments on heterogeneous ice nucleation, performed to understand ice clouds in the Martian atmosphere, show that the formation of a new ice layer on a silicate surface requires a substantially higher water vapour pressure than the deposition of water vapour on an existing ice surface. In this paper, we investigate how the difference in partial vapour pressure needed for deposition of vapour on water ice versus heterogeneous ice nucleation on silicate grains influences particle growth close to the water ice line. We developed and tested a dynamical 1D deposition and sublimation model, where we include radial drift, sedimentation, and diffusion in a turbulent protoplanetary disc. We find that vapour is deposited predominantly on already ice-covered particles, since the vapour pressure exterior of the ice line is too low for heterogeneous nucleation on bare silicate grains. Icy particles can thus grow to centimetre-sized pebbles in a narrow region around the ice line, whereas silicate particles stay dust-sized and diffuse out over the disc. The inhibition of heterogeneous ice nucleation results in a preferential region for growth into planetesimals close to the ice line where we find large icy pebbles. The suppression of heterogeneous ice nucleation on silicate grains may also be the mechanism behind some of the observed dark rings around ice lines in protoplanetary discs, as the presence of large ice pebbles outside ice lines leads to a decrease in the opacity there.

scholarly journals Photophoresis on water-ice particles induced by thermal radiation in protoplanetary discs

2012 ◽  
Vol 58 ◽  
pp. 209-212
Author(s):  
J. van Eymeren ◽  
T. Kelling ◽  
G. Wurm ◽  
S. Hagenacker
Keyword(s):  
Thermal Radiation ◽  
Water Ice ◽  
Ice Particles ◽  
Protoplanetary Discs

Sticky Ice Grains Aid Planet Formation: Unusual Properties of Cryogenic Water Ice

2005 ◽  
Vol 620 (2) ◽  
pp. 1027-1032 ◽  
Author(s):  
H. Wang ◽  
R. C. Bell ◽  
M. J. Iedema ◽  
A. A. Tsekouras ◽  
J. P. Cowin
Keyword(s):  
Planet Formation ◽  
Water Ice

scholarly journals THE STICKINESS OF MICROMETER-SIZED WATER-ICE PARTICLES

2014 ◽  
Vol 798 (1) ◽  
pp. 34 ◽  
Author(s):  
B. Gundlach ◽  
J. Blum
Keyword(s):  
Water Ice ◽  
Ice Particles

scholarly journals Ice Microphysics Observations in Hurricane Humberto: Comparison with Non-Hurricane-Generated Ice Cloud Layers

2006 ◽  
Vol 63 (1) ◽  
pp. 288-308 ◽  
Author(s):  
Andrew J. Heymsfield ◽  
Aaron Bansemer ◽  
Stephen L. Durden ◽  
Robert L. Herman ◽  
T. Paul Bui
Keyword(s):  
Doppler Radar ◽  
Deep Convection ◽  
Particle Growth ◽  
Dual Wavelength ◽  
Size Distributions ◽  
Temperature Growth ◽  
Radar Observations ◽  
Ice Cloud ◽  
Ice Particles ◽  
High Concentrations

Abstract Measurements are presented that were acquired from the National Aeronautics and Space Administration (NASA) DC-8 aircraft during an intensive 3-day study of Tropical Storm/Hurricane Humberto on 22, 23, and 24 September 2001. Particle size distributions, particle image information, vertical velocities, and single- and dual-wavelength Doppler radar observations were obtained during repeated sampling of the eyewall and outer eye regions. Eyewall sampling temperatures ranged from −22° to −57°C and peak updraft velocities from 4 to 15 m s−1. High concentrations of small ice particles, in the order 50 cm−3 and above, were observed within and around the updrafts. Aggregates, some larger than 7 mm, dominated the larger sizes. The slope of the fitted exponential size distributions λ was distinctly different close to the eye than outside of that region. Even at low temperatures, λ was characteristic of warm temperature growth (λ < 30 cm−1) close to the eye and characteristic of low temperature growth outside of it as well (λ > 100 cm−1). The two modes found for λ are shown to be consistent with observations from nonhurricane ice cloud layers formed through deep convection, but differ markedly from ice cloud layers generated in situ. It is shown that the median, mass-weighted, terminal velocities derived for the Humberto data and from the other datasets are primarily a function of λ. Microphysical measurements and dual wavelength radar observations are used together to infer and interpret particle growth processes. Rain in the lower portions of the eyewall extended up to the 6- or 7-km level. In the outer eye regions, aggregation progressed downward from between 8.5 and 11.9 km to the melting layer, with some graupel noted in rainbands. Homogeneous ice nucleation is implicated in the high concentrations of small ice particles observed in the vicinity of the updrafts.

The dance of snow-lines

2020 ◽  
Author(s):  
James Owen
Keyword(s):  
High Resolution ◽  
Planet Formation ◽  
Solid Phase ◽  
Outer Region ◽  
Vapour Phase ◽  
Vital Role ◽  
Sublimation Temperature ◽  
New Process ◽  
High Resolution Images ◽  
Protoplanetary Discs

<p>Snow-lines are thought to play a vital role in the evolution of protoplanetary discs and planet formation at all scales. Snow-lines occur in regions of the protoplanetary discs where the temperature reaches the sublimation temperature and volatiles transition from the solid phase to the vapour phase (or vice-versa). However, in the outer region of protoplanetary discs (beyond a few AU), the temperature is set by the distribution of solids and their ability to absorb stellar light. Thus, the thermodynamics of the disc and the volatile phases are inextricably linked. In this talk, I will show this coupling is thermally unstable, and snow-lines continually evolve in regions of the disc that are marginally optically thick. Patches of the disc proceeding through a limit cycle, where volatiles in a region of the disc continually condense and then sublimate. Using numerical simulations of the CO snow-line I will show it can move 10s AU over 10,000 years, repeatedly. I will use these simulations to discuss how this new process may effect measured Carbon abundances, solid evolution and ultimately planet formation, making connections to high-resolution images of protoplanetary discs. </p>

scholarly journals Synthesis of water ice particles in a plasma chamber

2010 ◽  
Vol 115 (D18) ◽  
Author(s):  
S. Shimizu ◽  
B. Klumov ◽  
T. Shimizu ◽  
H. Rothermel ◽  
O. Havnes ◽  
...  
Keyword(s):  
Water Ice ◽  
Plasma Chamber ◽  
Ice Particles

scholarly journals Levitation Diffusion Chamber Measurements of the Mass Growth of Small Ice Crystals from Vapor

2016 ◽  
Vol 73 (7) ◽  
pp. 2743-2758 ◽  
Author(s):  
Alexander Harrison ◽  
Alfred M. Moyle ◽  
Marcus Hanson ◽  
Jerry Y. Harrington
Keyword(s):  
Ambient Pressure ◽  
Particle Growth ◽  
Diffusion Chamber ◽  
Copper Plate ◽  
Growth Data ◽  
Surface Kinetics ◽  
Shape Factors ◽  
Mass Growth ◽  
Ice Particles ◽  
Chamber Measurements

Abstract A levitation diffusion chamber designed to examine the mass growth from the vapor of small ice particles (diameter < 100 μm) at ambient pressure (≃970 hPa) and low temperature (T < −30°C) is presented. The diffusion chamber is unique in that charged ice particles are levitated by an opposing voltage on the lower copper plate with lateral stability provided by button quadrupole electrodes attached to the upper copper plate. The button electrodes are far from the ice particle growth region, allowing ice particles to grow free of substrate influences. Experiments have been conducted for temperatures from −30° to −35.7°C, ice supersaturations from 2.5% to 28.6%, and over growth times ranging from 5 to 15 min. The experiments indicate that mass varies nonlinearly in time and exhibits a dependence on initial particle radius and ice supersaturation in accord with expectations from theory. In contrast to expectations from spherical capacitance theory, the derived mass growth rates do not scale linearly with radius, and derived effective shape factors (capacitance normalized with radius) are approximately 0.5. Fitting the growth data with a theoretical model indicates that growth is limited by surface kinetics with deposition coefficients ranging from 0.003 to 0.02.

scholarly journals Micrometer-sized Water Ice Particles for Planetary Science Experiments: Influence of Surface Structure on Collisional Properties

2017 ◽  
Vol 848 (2) ◽  
pp. 96 ◽  
Author(s):  
S. Gärtner ◽  
B. Gundlach ◽  
T. F. Headen ◽  
J. Ratte ◽  
J. Oesert ◽  
...  
Keyword(s):  
Surface Structure ◽  
Planetary Science ◽  
Water Ice ◽  
Ice Particles

scholarly journals The IMPROVE-1 Storm of 1–2 February 2001. Part II: Cloud Structures and the Growth of Precipitation

2005 ◽  
Vol 62 (10) ◽  
pp. 3456-3473 ◽  
Author(s):  
Amanda G. Evans ◽  
John D. Locatelli ◽  
Mark T. Stoelinga ◽  
Peter V. Hobbs
Keyword(s):  
Liquid Water ◽  
Lower Layer ◽  
Leading Edge ◽  
Particle Growth ◽  
Cloud Particle ◽  
Cyclonic Storm ◽  
Melting Layer ◽  
Ice Particles ◽  
Research Aircraft ◽  
Particle Imaging

Abstract On 1–2 February 2001, a strong cyclonic storm system developed over the northeastern Pacific Ocean and moved onto the Washington coast. This storm was one of several that were documented during the first field phase of the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE). In the 1–2 February case, soundings and wind profiler measurements showed that a wide cold-frontal rainband was coincident with the leading edge of an upper-level cold front in a classical warm occlusion. Ground-based radar observations revealed the presence of subbands within the wide cold-frontal rainband and two layers of precipitation generating cells within this rainband: one at 5–7 km MSL and the other at 9–10 km MSL. The lower layer of generating cells produced fallstreaks that were traced from the cells down to the radar bright band at 2 km MSL. Observations suggest a connection between the subbands and the lower layer of generating cells. A research aircraft, equipped for cloud microphysical measurements, passed through at least two generating cells in the 5–7-km region. These cells were in their formative stage, with elevated liquid water contents and low ice particle concentrations. The microphysical structure of the wide cold-frontal rainband was elucidated by particle imagery from a Cloud Particle Imaging (CPI) probe aboard the research aircraft. These images provide detailed information on crystal habits and degrees of riming throughout the depth of the rainband. The crystal habits are used to deduce the temperature and saturation conditions under which the crystals grew and, along with in situ measurements of particle size spectra, they are used to estimate particle terminal fall velocities, precipitation rates, radar reflectivities, and vertical air motions. The radar reflectivity derived in this way generally compared well with direct measurement. Both the derived and directly measured parameters are used to determine the primary particle growth processes in the wide cold-frontal rainband. Above the melting layer, vapor deposition was the dominant growth process in the rainband; growth of ice particles by riming was small. Significant aggregation of ice particles occurred in the region just above the melting layer. A doubling in the air-relative vertical precipitation mass flux occurred between the region where sheath ice crystals formed (−3° ≤ T ≤ −8°C) and the surface. Substantial amounts of liquid water were found within the melting layer where growth occurred by the accretion of cloud droplets and also by condensation. Growth by the collision and coalescence of raindrops was not significant below the melting layer.

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